Wow, so much ignorance of the way blockchains work. And I do not mean that as a slam, but your statements acknowledge none of the safeguards that are built into the system. It is already bigger and more powerful than ANY other dedicated network on the planet, and the decentralized arrangement makes it practically invulnerable to theft. It has been calculated that at least 80% of the network would have to agree to "hack the system" and nowhere near that amount will ever happen, because we ALL have a vested interest in it working properly! BUT, (and this is a big BUTT) it is believed that the US govt. seized the Silk Road btc holdings, and all they can do with it is use chunks of it to try and affect prices, by selling at strategic times.
Counter to that, there has been a lot of positive input by governments around the world, in fact, JAPAN has recognized BTC nationwide, hoping it will bolster their economy! PLUS, the 2020 Olympics are in Japan, so there is an expected uptick from that alone. Projections are for steady increases over the next 3 years, and this is a big part of that.

Now I'm not trying to start a flame war, and I'd like to see you come back with some concrete ways that governments (or central banks, whatever you wish) can do to disrupt crypto currencies. I know they can pass laws against it, but not even China is doing that, in fact, quite the opposite. I have read that they are encouraging crypto currency usage...

As far as your manipulation of Silver and Gold, I fully agree. But the blockchain is beyond the control of governments. It is also speculated that an "E-Dollar" may be rolled out soon, using blockchain technology. IMO, that would be the best way of "controlling" cryptos, giving a "better alternative" for people to invest in. I would likely get into that one as well, at least for some early gains, it could really pay off if one invest early and gets out at the proper time. At least partially out. Might want to keep some for daily use...