That is actually a huge thing. Reagan was a horrible President, but a good actor and salesperson. He got everyone to believe that cutting taxes on the rich would make everyone's life better. The Republicans were just taking the government boot off the necks of the job creators.
We saw over 25+ years how that didn't work to the point that Reagan had to find money through backdoor taxes to plug the massive holes he blew in the budget. Then Bush 2 did it again and the economy tanked. While Trump's true believers are unlikely to ever leave him (unless he is actually nice to a Black person, Jew, woman etc...) the reality is that people are watching, and if they get hurt, they are going to blame the party in power. Republicans function best when they are out of power, or at least when they only control one or 2 branches of government. They do not know how to govern for the people at all. Now that they are in the spotlight, everything they pass is theirs. This plan is theirs and it will hurt a lot of people so the ones with half a brain have to understand that they won't be able to write this off on the Democratic Party. The Freedom Caucus, are just arsonists who bought into the Reagan, Fox, Alex Jones idea that government is the enemy, so they are just saying no to anything where government helps "those people"
The Republican position is untenable right now. Not saying there isn't room to worry, but for once, the Republicans are in a position where they actually have to govern and they don't want to.