Wouldn't they be able to use their computing power to take over the network and kill it? I'm sure Microsoft or Apple could if they wanted to, right?
It is called a 51% attack. Yes they can, with less than 100 millions $ they can buy enough ASICs to do that.
And it would be much more effective than trying to "ban" it or try to "manipulate" it
Hell, just look at what is happening, a single pool without even trying has almost reached 51% of total hashrate, so long for people that say "nah a 51% attack is so hard to do it is impossible"