Why there is so much communist propaganda on lemmy?

You're blaming communism for what is, like everything else, a people problem. It doesn't matter what system you're talking about, there's always bad actors and horrible people that you can point to and say "see? That's why it's bad!"

Also, you are 17 and only really have the knowledge that you have been taught, and minimal experience living in the larger world. Most everything far you have learned has been what others have wanted you to learn. Once you get into the real world for a decade or two and start experiencing a full life, your views will change.

Or you can resign yourself to a life in front of cable news and stay firmly locked into an opinion that others have given you.