Bettas are known jumpers (hence why their tanks need to be covered). I think it ultimately goes back to the fact they are carnivores, and feed on just about any bug or larvae they can get their teeth on. I'm sure bettas in their natural environment are well-versed in jumping out of the water to grab bugs resting on leaves that hang close to the water surface. Are they starving? I sincerely doubt it, bettas figure out 'begging' rather quickly.
Two of my current five are big on jumping. One of them is simply terribly impatient when it comes to food and will go for it as soon as he thinks you're close enough he can grab it off your finger. My other jumper generally does his best air time when it comes to the 'mirror game' that I play with my bettas once, or maybe twice a week. I've always found it quite funny that he hardly ever cares about the betta right next to him on the other side of the divider, but oh no, that fish in the mirror is simply the most infuriating thing ever, and he puffs himself out, dances back and forth, and will even jump out of the water in his attempts to 'get' that 'other betta'
he sees in the mirror. I really wish I were better with a camera, I'd love to somehow manage to catch a pic of him mid-leap in full flare.