many platforms regularly organize such giveaways or raffles to increase their followers and attract new users. As you said it doesn't cost anything just a little time and effort to participate who knows maybe one day your luck might turn around and you might win a big prize! It's like a lottery where you have nothing to lose but a chance to win. Winning $100 is definitely a big deal, especially when it's completely free. It's really smart to take advantage of free opportunities because there's no risk but a chance to win.
Participating in many promotions could be our chance to be the winner. That is what people did and although they can not win before, they know they still have chance to win. That is why they want to participate on the promotions that they can but if he want to follow, he need to check which promotions that he can join. Not many promotions have a low requirement so he need to choose what promo that suit with him. Joining in the promotions means he understand the risk so that should make him think twice before decide.