Simplest explanation: Big players are willing to operate at a loss to gain marketshare. Then when bitcoin hits $100k you're dominating the market and bringing in the big bucks.
Other than that, a person might not have access to the equivalent volume of BTC but have easy access to energy/miners. Additionally, depending on how you predict hash rate and BTC price to evolve, mining might have a better ROI.
https://en.bitcoin.it/wiki/Mining_hardware_comparison
The top one (other than the Dragonmint miners which are not listed) is the Antminer S9 which you can see was released over two years ago.
If you are aware of some new mining hardware that is much faster please let me know.