"Force them to sell at a higher price" ... so they decide the market?
Nope.
Miners have costs to cover, mining unprofitably and holding makes no sense whatsoever (you're literally better off turning off your rig, buying on the market and holding at that point)
Turning them on to acquire bitcoins at a higher cost to yourself than the market price just doesn't make sense, investment or not, it won't help you pay down your loan.
You're better off buying them from others at that point.
