Gambling can be fun for some people’s but not everyone will consider gambling is just for fun, because in gambling you need to deposit money, so of course one one want to lose intentionally in the gamble, everyone deposit their money to win, who's users take it fun, they also invest small amount, and they didn’t gambling in regularly but serious people’s regularly make gambling.
Mostly, we spend money to get fun. We spend money even if you play certain games, visit the zoo, or gathering with friends. So, it is not so different with spending money into gambling to get fun.