They are rather fun to collect and gamble with. When you place a large sum of them on a fight and the fight is taking place, it makes you that much more nervous. But, a good nervous cause it doesn't matter if you lose them.
Some tricks to obtain fast credits are;
create interesting threads to get a million responses
make the right gamble IE: odds, who should win
you can borrow
someone may donate to you
win contests etc.
Staying active on the boards will make your credits go uppity up up.