1. You build a bunch of new ASIC miners.
2. Start using the new ASIC miners to mine.
3. Put them for preorder on your website.
4. Start developing better ASIC miners.
5. Once you've created the upgraded ASIC miners, replace the old ones and sell them
6. Go back to 2. and repeat forever!
Essentially, they build their own top of the line equipment, and use it to mine. Once their old equipment is outdated sell it for profit. You've already profited from the mining, now they profit again from the selling, and they are probably selling for much higher than the cost of manufacturing them in the first place. They are probably making so much money.