I keep saying it but both left and right in your country would prefer to believe in conspiracies than deal with reality...
Question: how did you come to this conclusion? Do you happen to know tens of thousands of Americans and discuss their individual political beliefs and take notes? Or are you listening to the loudest, most repetitive people online/in the media who say similar nonsense?
Individual "leftists" may happen to buy into some silly conspiracy theory bullshit, but generally it's not a trait of those who lean left/democrat/progressive. You can try to convince me otherwise, but I'll bet you a dollar you fail. Because I *do* in fact live in reality. American reality. Don't rub it in.
It *is* a clear and obvious trait of a significant portion of the right/republican/conservative side of our voting population. They're proud of it. For fucks sake, Qanon is thoroughly batshit and I don't know of a single "leftist" who believes anything about it. I personally know Too Many republican voters who absolutely do believe in it. Tears in their eyes, honestly believe it. Blows my mind in the worst way.