Many people say that bonuses are a trap, but I heard from friends that sometimes you can really make a good profit from the promotional balance. Question: is there a casino where bonuses are really played back and you can withdraw something from them, and not just "played and forgot"?

Yes, bonuses can be profitable if you approach them wisely. Pin Up casino has just the right conditions - wagering x30-x40, without hidden withdrawal limits. I myself got ahead a couple of times with bonus funds - I just chose slots with high volatility and played carefully. I later withdrew about 600€, after wagering. The main thing is to read the conditions carefully. But here they are open and clear, they do not hide anything.