You could live in a closet with no plumbing. Doesn't mean it's going to be comfortable for you, or keep you healthy.
Bottom line, not wanting to get tangled up in heaters and filters and stuff is bad news for any fish you intend to keep. The "accepted" care for bettas is buy betta, put betta in bowl with water, feed occasionally, buy new betta within year. I've only had mine a few months, but he swims every inch of the 10 gallon tank (80 degrees) filtered by a Fluval C2, investigating every change in plants and arrangement of decor I make. I overfeed him, but he gets so excited when he sees me feeding the other fish that I can't help myself, by feeding him 2-4 pellets (the smallest by NLS, and they seem smaller than "betta" pellets, and occasionally frozen bloodworms or Omega One Flake) twice a day. I expect him to live a few years, barring any accidents.