I do speak from experience: I myself am the proud owner of a betta. His name is Feesh, and he's 4 years old and half blind, and a lot of the time I think he's dead. So far, he is not dead. Plenty of sites will have you believe you need to change your betta's water once a week, but as someone who's let it get so bad that her roommate's boyfriend once meekly asked, "Is he OK in there?" I know for a fact you can let that water sit for at least two months. After all, you live in the kind of squalor no expert would advise, so if you can live in a disgustingly dirty house, your fish can put up with it too.
Sometimes I show Feesh a little plastic dinosaur to make him mad (because it's good to make your betta mad so they can stretch their gills). Since I started working from home, I upgraded his tank from a vase I found on the street to a 2.1 gallon tank from Petland Discounts. I also got him a bamboo stalk from the dollar store, and some colored rocks from the dollar store, and a loose marble I found on the shelf of the dollar store, because the dollar store is like Ikea for fish. Then I bought him a little hammock, because bettas, like depressed people, apparently love hammocks. Then I ordered small moss balls on Amazon called marimo that take nitrates out of the water. Then I went to my psychiatrist and he doubled my meds.
I'm doing well!!!!
While sometimes I feel like the only sad adult with a betta, I know for a fact they're out there. Just today, I saw a woman walking down the street, holding a fishbowl with a betta in it. Instead of wondering what happened ("Did she just break up with a 9-year-old?"), I just thought, "There goes a depressed person."
I feel you, sister.