You're right in that it's essentially impossible to profit from mining YAC if you pay for your own CPUs and electricity. As BitJohn said, a good number of the remaining YAC miners are probably using systems that they neither own nor pay the electricity for (that's not to say they're all criminals 
so please don't take this the wrong way). I'd estimate -- and I have no proof to back this up, just guessing -- that the remaining YAC network hash power is split about 50/50 between people mining with GPUs and those who are mining with server farms/botnets.
To put things into perspective, I happened to be reading the forum at the moment that YAC was released. I began mining ~15-30 mins after release and within 24 hours I had 6000 coins using only a single Intel i7 3770k. Within about 5 days electricity costs began to approach the value of the coins that I was mining and I decided to halt my mining.
so please don't take this the wrong way). I'd estimate -- and I have no proof to back this up, just guessing -- that the remaining YAC network hash power is split about 50/50 between people mining with GPUs and those who are mining with server farms/botnets.To put things into perspective, I happened to be reading the forum at the moment that YAC was released. I began mining ~15-30 mins after release and within 24 hours I had 6000 coins using only a single Intel i7 3770k. Within about 5 days electricity costs began to approach the value of the coins that I was mining and I decided to halt my mining.