From my understanding, the price of Bitcoin can be affected by politics, the stock market, and macroeconomic factor. But its network is not. It is almost completely independent from those factors.
As long as nodes and miners continue to operate according to the protocol's rule, Bitcoin will never become centralized regardless of how its price is manipulated.
Even as the price is controlled by all these that you mentioned, the price of bitcoin is still increasing. If the politics, the stock market, and macroeconomic factor makes bitcoin price to go down, at last the price will still increase which will makes the negative news not to have effect on bitcoin in long period of time.
Regarding whether Bitcoin can be destroyed. I think we have already had many similar discussion, and most people believe that it is impossible.
What if the government all over the world go against bitcoin? This is far from happening but it is possible. Although I understand you, even what makes bitcoin to be a success, it shows how difficult it will be for such to happen.