I bet if you put a betta in a 120 gallon tank by himself he would be perfectly happy, not overwhelmed. He'd establish himself a nice territory around a piece of driftwood and some plants for hiding in and wait to be fed and probably live extremely happily.
Also.. almost any girl ages 12-40 would probably love to live in a mall.
I think it was OldFishLady who told me when I first started getting on forums and learning how to properly treat bettas that "there is a difference between thriving
" we as owners have to decide which we want for our fish. Do we want them to merely survive in a tiny tank, probably to die in 1-2 years if he's lucky or do we want them to thrive in 2.5 gallon tanks or larger with heaters to live happily for a normal life expectancy of 3-5 years if not more?