Diet and maybe workout for a few weeks, depending on what your tummy looks like to begin with. For me it wouldn’t take much - I’ve got a pretty flat stomach anyway.
To get BS’s money:
Either:
Win the lottery.
Spend years shrewdly investing your life-savings in the stock market.
Have a very wealthy relative die and leave you all their money.
This is the easiest question I’ve ever been asked. The money! Durrrr!! I’d live with a pot belly any day if I had a bazillion dollars! Luckily for me, I don’t have a pot belly… or a bazillion dollars