Firstly there are ASIC miners, which will not sell HUSH for anything less than their cost to mine it. HUSH is compatible with the same miners as ZEC, ZEN, KMD, ARRR and a few other coins, so very large farms have the potential to switch to the Hush network. Autoswitching software does this automatically for large miners.
Miners also have capital costs, the cost of the mining equipment. When they buy new equipment, they are more likely to sell and less likely to HODL, until they break even.