I've been working on CPU mining for a long time. I think it's for someone who does not have that much money for a very expensive graphics card and just wants to make a few bucks along the way, the easiest thing to do is run their PC. Unfortunately, there are not so many coins where you can really believe that you can earn something more than its electricity costs. I also found ROI https://bitcointalk.org/index.php?topic=2361848.0 or Hodl https://bitcointalk.org/index.php?topic=1317918.0 or Dynamic . I think that even with these CPU Coins maybe can not rich, but the next vacation or the small car is quite possible.

Sorry for my bad englisch ....

Guru