One of the things I learned about making money online is that people benefit from a percentage of many of users' actions. It could be that people are serving up lots of ads around your quizzes and games, or that the information you provide is somehow being harvested for research or third-party companies. One out of every 100 game players might click on an ad. Or the site might be doing A/B split testing for free, determining which page background looks better.
However painless playing a game is, there's always some ulterior motive, whether to take your data or money, for the webmaster to host the game.
It all comes down to the rest of your life and whether you're happy and productive or not. If you're sitting there playing hour after hour of games and just living out a marginal existence, then maybe you might like to see if you're an Internet addict.
On a more positive note, maybe you have enough experience seeing what works for quizzes and games, and you might be able to make your time more productive and lucrative by making up a few simple quizzes or games. The tools are out there if you really want to give it a try.