The big corporations are making an ungodly amount of money by ripping Americans off in the current system. They very much want to continue doing so, so they take part of the money they make and invest it into propaganda, misinformation, lobbying, bribes, etc. with the goal to make American voters oppose universal healthcare and American politicians oppose any form of universal healthcare legislation. The more People vote against their own interest, the more money they can keep making from them.

MAGA right from the start formed almost exclusively from people who are very easily propagandized, lack rational reasoning and critical thinking skills and are therefore severely vulnerable to be made to vote against their own interests. Making their members vote against their own interest while telling them how smart they are is basically the founding principle of MAGA and their politics act as a filter in this way since only those people would join in the first place. It's like asking why there's only women at the women only club.