This doesn't just apply to Trumpets, it applies to everyone who thinks we should mantain the current status quo or roll back to a previous one. It only really takes a basic look at history to understand why. In pretty much every time period, no matter where you look, society has always tended towards a liberalization of itself. The progressive groups have almost always won in the end, and, when they didn't, the country pretty much went to fucking shit. The conservatives have always been the bad guys.

You don't even need a thorough understanding of history to realize why right wing politics are bad. Just look at all the things we consider bad nowadays (Unless you are a monarchist or a neoreactionary in which case go fuck yourself): Slavery, monarchy, lack of rights for certain groups. The people who fought those things were always, without exception, considered extremely radical for their times. What makes you think progress should stop right now? Do you really think that, after milennia of unimpeded progress, we have reached a point where we should be comfortable and things should stay this way, even though, again, just reading history will show that progress will eventually happen because people don't like losing rights?

TL;DR to be a Trumpet is to be historically illiterate.