We do know, skilled workers who have decent jobs don't risk their lives going through an unforgiving desert. The ones who come are desperate and poor. For the most part they go to slaughterhouses, farms, construction, janitorial services, and landscaping, not exactly skilled work. The farming lobby is 100% not wanting a sensible immigration to pass, because they can get cheap illegal labor. I've spoken to a Republican congressman in person about this (my uncle is a donor), and he told me blaming illegals is a smokescreen to protect farms and like businesses that hire illegal workers.
Regarding amnesty, the greater numbers had nothing to do with it. Illegal immigration went up because of 9/11, when borders were shut. Before that, workers came back and forth seasonally, and border guards didn't really care either, it was an understanding. As far as becoming citizens, the party who did that would have millions of votes coming their way. I guess there isn't much difference between being a permanent resident and citizen, but if someone is living here for a long time and contributing to society, why not? To send a message they are lesser? That just creates unnecessary resentment.
Regardless if extra revenues are used for the deficit or not, they are still extra revenues that can be used to help the country. You're making a talking head assumption.
Trump will never ever go down as a hero. He is despised worldwide and by half the people in his own country. He's not fixing anything, he's making things worse that will make it difficult for the next president to fix. The countdown to his demise is on, either the election or Mueller will lead to it.