Because of the effect and outcome of gambling as a risky activities where there can not be certainty of getting anything at the end of the day.
No one can have a definite advantage or outcome from gambling, if a gambler wins, he doesn't really benefit because if you count from defeat, all the wins are not comparable.
All gambling activities, whether it's games or betting, have a high risk, unless you only use a demo account, maybe risks can be avoided, but I'm not sure anyone can survive just playing with a demo account.
Gambling is a choice so we must be able to be responsible and accept the risk of what is our choice.