A welcome bonus is not a gift. It is a loan with rules, and the cost is always in the lines under the headline.
The first line to find is the multiple. Thirty times the bonus sounds abstract until you do the arithmetic: a 100 bonus at 30x means 3,000 in stakes before you can withdraw. Some sites multiply the deposit as well, which doubles the hill. If the multiple is buried or missing, treat that as the answer.
Game weighting decides what counts. Slots often count in full; the games with better odds may count at ten percent or not at all. Max cashout caps what you can keep, so a lucky run can still end at a fixed ceiling. And the clock: most bonuses expire in days, not months.
Sometimes the right move is to decline the bonus and play cash. A smaller stack with no strings often beats a bigger one with four.
If you would like to learn more about the technical workings of provably fair algorithms, you can download the whitepaper.