Trump is hated because the border wall thing threatens routes used for trafficking drugs and humans...
So you think the Democratic Party supports human trafficking and (since the Nixon era) cross border drug smuggling? You have seriously misunderstood both the opposition to Trump's immigration policy and the government's anti-drug efforts over the last fifty years.
I think there are a lot of rich liberals who like recreational drug use and they would like it legalized ideally, but if it's not legalized, they will still go on using privately and there are people who want their (big) money badly enough to do all the horrible things like human trafficking etc.
Now I'm not saying there aren't any rich illegal drug consumers that are Republican, because there probably are, but generally the Republican party is not going to support legalization or oppose the war on drugs the way Democrats do (with varying rationalizations about treatment being more effective than criminalization, etc.). Nixon launched the war on drugs and was/is bitterly hated for doing so.
The people who enjoy recreational drug use (and those who make money serving them) don't want to stop what they're doing just because the government makes a policy to stop them. Look at all the atrocities you read about in Mexico having to do with cartels. It is a nasty business.
Democrats support a path to citizenship for migrants and for the illegal aliens already here, not human trafficking,. The disgust with Trump is because he conflates the two for political purposes.
Obviously the principle of liberty should include liberty to migrate responsibly. Unfortunately, there are widespread abuses of liberty to exploit and abuse others (not just drug and human trafficking). Such abuses and exploitation occur both intranationally and internationally, but when they occur internationally, borders are a tool for intervention; one that would be much harder to implement intranationally by increasing interstate border control, for example.
But I will be the first to agree that when global peace and cooperation finally stabilizes without ulterior motives and covert conflict, strife, and exploitation; everyone will be able to sustainably migrate and work, get healthcare, etc. wherever they want. You'll be able to travel and stay anywhere in the world for as long as you want, and it will be easy to find paid employment without being a citizen, and it won't even matter whether you are the richest or poorest person on Earth, because no one will have any criminal intent whatsoever.
I know it sounds about as utopian as the hope that recreational drug use will go away on its own tomorrow, but wouldn't that be great too?
The importation of illegal narcotics occurs primarily through freight shipments into air and seaports but the largest sources are domestic. The Democratic Party didn't support the legalization of drugs in the Nixon era and doesn't support the recreational use of use narcotics now. The slow legalization of cannabis occurred because its criminalization came to be seen as irrational by Democrats, Republicans, and independents.
You split hairs. Take a step back and look at the bigger picture.