How come a promotion is a scam?
Promotion is just a marketing strategy to most businesses including the gambling casino, their main target is to attract lots of customers to play on their casino. The offer may seem to be smaller to you but for the other gamblers, it is enough already, at least they got some bonuses with that promotion. It is up to us too to find whether we like to play on that casino or not since nobody is forcing you to play on that site.
He didn't said all promotions are scam. It's possible that some promotions could become a scam because sometimes casinos hide the terms and conditions of the promotion and could suddenly add an extra rule once a player starts winning too much than expected. I agree that we're not forced join a promotion but it's hard to avoid when it seems like free money.