I had this argument plenty of times, as I visit USA often.
The fundamental problem is that Americans think they are the best at way they do, because they do something that no one (or at least they believe no one) else does outside America. Americans have a huge pride and pisses them off to no end that someone from the outside can come into the country and do a better job than them. Period. This is the root problem with H-1Bs and everything else is indirectly linked to this.
I always hear the same arguments coming from Americans regarding to H-1B or Outsourcing, like "They just bring those workers because they are cheaper, so it doesn't matter if they are worse!" or "They sent to India but those guys are terrible at doing their job!".
To understand why you already lost, you have to accept the fact that other people is as good as you or better outside America. I'm not talking about bringing Mexicans to do construction work, I'm taking about scientists, engineers, etc. There is PLENTY of birllant people outside, and guess who do they work for? Their local companies and governments? Some might, but they will work for the highest bidder and that includes American companies and American government (through companies). Most of that people is in countries where the standards of living are cheaper or much cheaper, and with an entry level American salary they are rich, have their whole family and they don't care about H-1Bs.
That is the people responsible of less jobs for the Americans, and you have no idea how many are there, probably more than americans themselves. Remember that I mentioned at the beginning of the post that I travel often to the USA? Guess why. America makes it very easy for foreigners to open an American company.
So, complaining that H-1Bs are responsible for the loss of jobs is like blaming a cold for the death of a patient with HIV.
In fact, if you were not short-sighted, you might even see the positive side of having foreigners come and work in american soil. One foreigner will take away at much one job, but one foreigner can also create many jobs, and they don't need to be Elon Musk or Satya Nadella.
But no blaming your problems on those inferior immigrants. Right. I can tell you that there is plenty of jobs and plenty of people willing to invest in endless amount of opportunities in America, Been in many countries and no other country compares to America in this regard, your country is the best.
Also met and have known of more foreigners living outside America taking these opportunities than there are individuals under H-1B.
So, if you are worried about your job or unemployment, it definitely is because you either are not qualified, relevant , or affordable enough. That's the hard truth. America is a free country and promotes free trade with every other country. Vote for the national socialists next time there are elections if you don't like this.