I'm not into sport or betting, but clicking on their posts costs me little time and no money. I just guess the winner and win a few, although I've not been paid by them in a few days. They must be doing well from all the SP they get. I notice they get more votes on the post than on the comments, but that's probably just the many bots.

I do think Steemit should make it easy to implement games here as a lot of people like that. If it keeps them coming back then it's good for the site.