If you're big on America First, why wouldn't you want the best foreign entrepreneurs to come and found great companies that generate American jobs, American taxes, and American products?
You can, of course, disagree about whether that is a valid or justifiable impulse (and I'd be inclined to agree with you on that). But it's not a mysterious or even unusual one. Heck, we have a founding EU member state on the precipice of fracturing along a linguistic boundary. Certainly, if the shoe were on the other foot and a huge fraction of people running major Indian or Chinese businesses were American immigrants, lots of people would be pretty upset.
You probably take it to mean natural American leadership in business / science.
Others - those who probably identify more with the statement - take it to mean that America should put its domestic interests first. Now, denying visas to entrepreneurs probably would be a policy that harms American interests but it's not high up the list and the dissident rightists have an incentive to mess up immigration as much as possible - it'll give them a better position to renegotiate an immigration system.
I think the primary problem with our immigration system is that both sides represent corporate interests in that they want a companies to have access to inexpensive workers and so we get problems like H1-B that make it difficult for H1-B workers to change employers or negotiate a higher salary / better position.
The other problem is that people with left-wing sympathies want an immigration system that works better for people who aren't poised to do skilled work and they know that they can't cut separate deals on skilled immigration and unskilled immigration because unskilled immigration isn't as politically desirable.
Blame uneducated voters, sure. But there's a reason we're not doing the thing that's clearly right here and it's not because of Trump's base.
Imho because it's implicit signaling of `Americans First` (and here implicit only a subset of them)
What's that quote again... "Never attribute to malice that which is adequately explained by stupidity."
And while it's true that the white rural poor vote Republican, as a political force they aren't that potent. It's unfortunately, because their interests often get steamrolled by more corporate-oriented Republicans. Democrats throw their arms up and say "Stop voting against your interests!" but neither party has any coherent vision for rural America. Republicans see them purely as culture voters, and Democrats are focused on giving them the same complicated means-tested benefits as everyone else.
Just like with other aspects of the labor market (agriculture, hospitality) where illegal immigration undercuts Americans, VCs are doing labor market arbitrage and are importing cheaper "founders" who essentially become visa hostages. It doesn't benefit anyone except the silicon valley elite, who also run this site, incidentally.
No different than any other capitalist investor!
I am not sure how essential is this visa category, since there are other categories most founders would qualify under.
These are people (including me) who come in here and build a bunch of local connections. Turning it personal, Our kids go to school here. I own a house here. I have a ton of friends here. I pay taxes and donate/volunteer when I can. I ride bicycles everywhere if that matters. (No I am not blue/democrat because I can't vote :).
You are also touching on other issues like visa hostages. Most of those people who feel that they are in a 'hostage' scenario can go back anytime they want but most of them choose to stay. I say most because there are definitely a few who can't but whatever.
In my case, I could've stayed back in India and worked for similar companies (Both my prior companies have a big presence there), but here is where I want to be. Now you can say me being here ONLY benefits my employer or elites, but I definitely don't think of that way: I think of it as an incredible opportunity and like any other big-system process, it has its troubles. ¯\_(ツ)_/¯