Americans should understand their own immigration system before making these claims. Look at the numbers and the dynamics, and H1Bs aren't a threat to you:

- The number of new H1Bs issued per year is 85,000, capped by law.

- The total number of H1B holders today is around ~500,000, per USCIS and DHS.[0]

- H1Bs require bachelor degrees minimum to be granted a visa, which means they only compete for white-collar jobs. Let's assume all these H1Bs are software engineers, for sake of argument, and not university professors.

- The total labour pool for tech is around 6.7 _million_ per the Bureau of Labour Statistics (https://www.bls.gov/cps/cpsaat11b.htm, look at computing and mathematical operations section)

This works out to about ~7 percent of the total labor force consisting of H1Bs today. At 85k per year, it would take about five years to double that population to about 1 million. In that same time span, the US is expected to add 4 or 5 million in population growth alone - I don't know how you want to assume the tech labor pool grows, but I think it is silly to claim the population of H1Bs is a threat to the country's domestic labor pool.

You specifically talk about undercutting wages. H1Bs are supposed to be paid fair wages for their roles as everyone else per wage parity rules, precisely because they're not supposed to be preyed on or represent a displacement to Americans through cheap labor. Companies that attempt to skirt these rules use two techniques: deliberate underlevelling, so that highly qualified folks are categorized as lower-tier workers in occupations / categories other than their actual expertise so that companies can claim a lower wage, and contracting them to other employers at those wage rates. Meanwhile, the H1Bs for those companies can't actually enjoy job portability and escaping these constraints because switching jobs requires a transfer petition and risk, nor can they report their employer because getting fired means deportation. That is how H1Bs end up undercutting wages: not by design, but by abuse and captivity.

I have little patience for this sort of hand-wringing because the ire tends to be pointed and directed at H1B holders for simply existing - not at the institutions that game immigration law, not at a system that stifles legal immigration and blocks other pathways, not at a system that is too busy making the lives of immigrants harder than actually holding abusive actors accountable. There'a a perfectly reasonable system of reform that targets abuse and benefits everyone, but nativists don't want to exist with "foreigners", so they choose to punch down instead of up and claim self-defense. Such reasoning is, frankly, puerile.