Does a bookmaker you play on do something sort of this apart from free slot spins that you can redeem your winnings (play x game and double your winning in case you win or play z game and get back 50% of your bet in case you lose) only by playing your own money later?
No, unfortunatelly I have never seen a promotion like this disponible at crypto casinos. It looks like it's an exclusivity of fiat bookmakers. However, if crypto gambling platforms adopted this kind of promotion I would participate without hesitation, even if it would be necessary to go through KYC process. Sometimes we have to show our identity for much less, so I see no harm in doing this for 10$ or 20$ in btc, for an example. There is nothing wrong or illegal on it, right? So why to fear?
I just wouldn't take such promotion opportunity if the terms were too abusive, but I think it shouldn't be an issue, since the name is *birthday gift*, so it's supposed to be a gift for real.