botnets
I am surprised how little attention this gets. There are hundreds of people making $10k+ per month with botnets.
Hmm. Hundreds x $10k+ = millions of dollars per month. 50 BTC/block x 144 blocks/day x 30 days/month x $11/BTC = $2.4 million/month.
TL;DR: You're wrong, there can't be "hundreds of people making $10k+ per month with botnets". Tens, maybe.