Sometimes that's not quite how it works. Right now, there's a gold rush in that space for customers. They want to sink their hooks into the most customers and deprive their competitors from doing the same. So they are really aggressive with the ads...like offering $200 in "free bets" for you and a friend you refer once that friend deposits/bets as little as $5. They may be frontloading their ad expense in the knowledge that any customers they acquire now will more than make up for it.