Actually that's a huge misconception, Pumba. They prefer larger areas of water, and anyone who's seen a beautiful betta swimming around in 3+ gallons doesn't want to put them back into those tiny cups.
That is true, the whole "betas live in 3 drops of water" story gets old fast for people in the know. Betas actually prefer big tanks. I used to have one in a 5 gallon tank that loved it!