I do not believe much in welcome bonuses, because when a deposit is made and if I make a profit I want to withdraw my money, but if a welcome bonus is accepted, it is conditioned on the fact that you have to make a high wager and sometimes make enormous amounts, And that doesn't make any sense to me, because it compromises the money and it can't be withdrawn, that's why I don't like to accept the welcome bonuses, there are many who say that they do, but that's leaving the money in the casino.
You are right. Many gamblers sign up on casinos, mostly new ones, and make deposits just because of their lucrative deposit bonuses. But they forget about the wagering requirement which, statistically, will drain their entire balance and they will end up with nothing to withdraw.
However, if you gamble for fun, you certainly will not refuse such offers because you made the deposit and don't mind losing it.