I see it as them running two business models:

1. Mine the coins themselves (which they do)
2. Sell miming power to others

2 revenue streams work together but they also work apart. The main goal for them is to mine coins themselves but they hedge that by also selling mining power to others. If bitcoin were to drop a lot they get the extra income from miners.

I mine both bitcoin( 16th/s) and x11 litecoin (70.125 mh/s) and I get $15 a day on a $2500 investment. I could take the money but I choose to reinvest it.