Unless someone is able to massively adopt bitcoins with at least more than 60% of the bitcoin supply he holds, however I think it is very unlikely anyone can adopt more than 60% of bitcoins.
What's the reasoning behind 60%? And what power does that grant, other than financial?
No one can control bitcoin is true, but I doubt when you say bitcoin price is not regulated. Although bitcoin is decentralized but bitcoin price is being listed on centralized exchanges, so price correction is possible, as long as the government really wants to crack it down, then bitcoin price regulation will not be too difficult for them.
When the government intervenes with regulating prices, it does it to either protect the consumer or the producer, and it does it to products that have inelastic demand. Bitcoin doesn't have that, it's quite oppositely seen as a luxury product by most. As for producers, I'm quite sure governments aren't going to ever pay part of miners' expenses-- nor should they.
Also, bitcoins are everywhere and nowhere. Good luck on catching violators.