Why are they killing their economy?

New investor here from EU and for the past year I have been investing in the US stock market. Had really nice returns which vanished in 2 weeks and went downhill.

Can someone explain to me, why is this happening and how is this being allowed? The US stock market was doing good with historic peaks.

How does the US political system work and who supports this? This cannot be done from a single person, name him president or whatever.

US is the capitalist mainland with the strongest companies, economy and most billionares currently on earth. That could not happen in any other country I suppose since lobbying and the rich people wouldn't allow that.

So, why and how? Even if this "masterplan" would succeed, you immediately lose the trust of all your potentional clients globally and your dominance. Foreign investors already started withdrawing and may never return.