Fish don't need interaction like cats or dogs do, since it's not as though you can reach in and pet them or play catch with them. Generally, as long as your fish can see you for at least part of the day (ie. they're in the same room as you) and you come over to see them occasionally, feed them, etc, they should be fine on the "human interaction" level.
A better word for describing what can often cause fin-biting is a lack of stimulation; that may come in the form of human interaction, but it can come from many other places as well. Your tank should large (2.5+ gallons at a bare minimum) and filled with hiding places, plants, caves, etc--lots of things to "do" for your betta. I have a small/young betta that I just placed in a 5G and although he was fin-bitten when we purchased him, he's healing up nicely and has expressed no interest in fin-biting since his tank is so full and has lots of hiding places! Some bettas also really like marimo moss balls and will push them around, things like this can also provide entertainment for your betta.
Ultimately, some bettas are just fin-biters though. In the same way some humans don't like to have long hair, some fish don't like to have long fins. If you're sure your betta has a great setup and you interact with them as often as you can, he may just be a chronic biter. The best thing you can do for him is keep his water clean. :)