I breed HM, PK, & HMPK. I dont really favour bettas out of those tail types. Just personal preference for the most part. I also currently favour the koi colour variations highly.
Bear with me because my reply to your question will probably be pretty lengthy! haha
Pet store bettas are off the list for me for a few reasons. 1 being you never 100% know where your fish are coming from. Wether it be warehouses, local hobby breeders, leftovers from proper Indonesian breeders, Etc. Talking local pet stores these are all possibilities. Most of my non-chain pet stores get their betta from goodness knows where. And most of them arent very high quality. Now its said chain stores like Pet Smart & Petco (just to name two highly popular for buying betta) that they get their bettas from indonesian breeders. Which is highly favored over warehouses. If they do infact however get their betta stock from indonesian breeders. They get the low class bettas. The "leftovers" if you will. Ones with tore up fins, maybe not the prettiest, and just in general whatever is left that the breeders personally wont use elsewhere. If this is the case, the fact that they get whats considered "lower class betta" isnt an immediate bad thing. As im sure everyone has seen. Pet smart & especially Petco can and do have some pretty fish. However pretty or not. 99% of the time they arent nor will they ever be my first choice for breeding personally. However for a person wanting to jump on the bandwagon of having a "inexpensive easy to care for pretty fish in a vase in the house" yeah. They work great. Hence why they sell anyways.
You may not have this issue at all if you have a great "local" pet store near you who you've personally talked to about where their betta come from. And they have great connections. Or if you have a actual betta breeder/store within your area. If you do, lucky you. Its rather rare. At least in North America.
Now my issue with not knowing where the fish came from- pretty or not. Is you have no idea what potential that fish is carrying. All genetics, diseases, genes. All things that can and will carry onto your spawn. Now like I said- if you're just someone wanting a pretty fish for a vase in your house (which betta fish are notoriously popular for) These fish work fine and quite honestly- it doesnt matter. No it cant be guranteed any betta you buy will be 100% clear from carrying a number of things. A lot of them carry a lot of different genes and genetics. Even straight from indonesian breeders. But its a hell of a lot safer & pure and more guranteed than a fish from Ex; petco or petsmart.
2nd is I simply dont like to support most pet stores regarding their care for Betta fish. This unfortunately goes for chain stores "and" local in my personal experience. Just today I went to my local pet store. And could point out several out of 25 fish that were in dire condition. Swim bladder issues, clamped fins, fin rot, some with no fins at all. And probably 15 that in general had starting fin rot/had fin rot. Non of which were getting the care they needed
Unforunately face it. Bettas are a highly misunderstood fish. Being explained from the get go as a "hardy and easy to care for fish" which they are & they arent. They're essentialy in the same pool as goldfish when explained. Just put them in a bowl, feed em. And you're good. Which isnt the case. Theyre susceptible to many diseases meaning their water needs to be in prime condition. They are a tropical fish that NEED warm water. So though easy and simple to care for if you know what you're doing. It becomes the opposite when you dont know what you're doing. And it all gets thrown to luck and chance. Put them in their vase, and hell if your house is warm enough and you just so happen to switch out the water enough. Yeah, by chance and luck. Theyll last a while. So of course pet stores do the same.
Most pet store owners probably dont even know 100% the care required for bettas. All their potential diseases. Etc. What you or I may notice and immediately diagnose as the start to an issue when looking at bettas in a pet store. Many store owners wont even notice- at least no till they are noticeably in pretty bad shape. Hence why they get there in the first place. Because Bettas make up a VERY SMALL portion of pet stores (unless again- you're lucky enough to rarely have a all betta store in your area) Otherwise typically bettas take up a small section, shelf, or rack. Of a very large store filled with tons of other aquatic life. And essentially they take up that much of the owners mind & priority for them as well. A very small portion. It also becomes an issue that betta cannot be put together like our other fish. Its not like you can throw 10-50 Betta into a prime tank together and you're good. Once of age every, single, one of them, need their own space. Therefore "laziness" replaces "ideal conditions". And its not like betta are big fish or fish that come in small numbers. Its like having tetras or goldfish except they all need to be seperated. People get lazy. Im sure betta would be in much better living conditions in pet stores if they could be in one tank that could be monitored and watched. But all individual places? forget it.
Long story short bettas often take up a small portion of pet stores as well as a small portion of peoples priorities. Leaving them 90% of the time in not good conditions and care. Therefore I simply dont like to purchase into it or support it. We choose to make living animals a business- therefore like it or not. We should be caring for every one of them appropriately. If we cant. We shouldnt be doing.
*I am not refering to Bettas living in cups and very small areas. Though unforunate and though even this is something that can and is abused. As a breeder and once again a fish that needs to be seperated yet comes in large ammounts. As a "holding" space it simply works best. However as a lifelong space is another story.
So though I have my multiple ifs and ands about why I prefer not to purchase my Bettas from pet stores. It is mostly due to when you're in something this deep. You want to do it best and right. When in bettas we are all notorious for focusing on color and tail type, thats it. After all that is what bettas are popular for. Bright, colorful, with pretty fins. And unforunately thats what a lot of breeders mainly focus on in this world of deeply varied fish (if all betta came in one or 3 variations im sure wed start focusing on finer details) My best way to get my point across is this. Would a good & consistent breeder go ahead and pick up their breeders from Pet smart? No. They probably and very often have connections or other good breeders they get their stock from. You want a solid foundation
If I just wanted a pretty fish for the house im sure the pet store would be my place. Hey if i decided to start a community freshwater tank im sure a chain pet store is where id be hitting. But thats not my case. I am a pretty involved betta "breeder" and owner. I like the craft of these fish at their highest and most genuine quality. Straight from the source. Especially when breeding them. I like to go right to the breeders. To know their quality and genetics. And to know their in the best care they can be given whilst in their sellers hands (im sure there are horrible breeders out there dont get me wrong)
As said I dont like to support pet stores for their level of care given- that I personally witness again and again. I appreciate the craft and work that goes into breeding, raising, and caring for these beautiful fish. Rather than purchasing them in a plastic cup from a pet store & there you go. The way I view it would I rather breed horses that are mixed mutts from all hell, no idea what their genetics are, breed is, potentially bad conformation, but hey their colors are pretty. Or two well rounded horses that are purebred & whos backround I know, etc (if you know nothing about horses at all this may just have no meaning to you, haha)
Though its definitely both the cheaper and easier route. Its not my prefered both morally and with my standards for what I personally do. I know a lot of people that are hobbyist betta breeders and owners and get all their fish from pet stores like pet co. And thats their opinion and decicion. If I was planning on breeding a small spawn or two just for fun im sure I might too. But thats not my case. Im pretty invested in this therfore I have a higher route for doing it.
Sorry for the late reply tardigrad! And if you made it through this entire reply kudos to you big time- should be shipping you a free fish. haha.
Would love to see some pictures of your fish! Always fun to share :)