- you can't just buy 15% of the hash rate
depends on who you are
Go ahead and make a list of costs and constraints (manufacturing, logistics, etc.) for achieving 15%.
Please, take into account the time necessary to build these 15% (currently 50 PH/s) from scratch; and your actual hashrate share by the time you're done...
Finally, make a list of actors that could meet those costs and actually be able to achieve 15%.