We do hear this often times.

Everyone who gambles for money will be disappointed because it's unlikely that they'll hit their goal on a daily basis and compare it with their daily rate from their employment or jobs.

That's why, gamble only with the aim of having it as a hobby and to have fun. Limits should also be there and don't gamble with what you cannot afford to lose. It'll make you crazy when you lose it and you'll get into that cycle that you'll have hard time to break.