People want money fast. I have work for bookmakers and online casino's. Clients don't take into account the risk, all they look for is the reward. Another classic version of this is lotto - everyone fantasizes about winning millions overnight.

Horse racing is very popular as is sport. To be honest I do not mind that type of wagering, if it is done in a controlled environment and for fun.

Poker machines on the other hand are a degenerative cancer that will suck more money, the more you play. I have examples here in Australia of people who have lost >$2m in 6 months on machines. All they are is a licence to print money as they are set to take between 7-12% of revenue based on turnover.