Rich people like Elon and Vivek love legal immigrant high skill workers because they won't complain or stand up to them. They are happy to be here and be yes men. Yes sir, I'll work overtime. Yes sir, I don't have family here so I won't take any time off. Yes sir, I will make you a lot more money.
It's all about money to these elites. We're all just numbers in a spreadsheet to them. The legal immigrant workers cause less problems for their bottom line. That's it.
They have to stay employed while on an H1-B or else they have to leave the country. They can only switch jobs if the new employer is also willing to sponsor them. Sponsoring the visa is a bureaucratic process that smaller companies rarely bother with because it's not worth the effort if you aren't hiring in mass.which means they have a limited job market. So they rarely change jobs until they get a green card which takes years.
A lot companies employ a strategy of throwing a lot of cheap bodies at a problem. They are the perfect employees for that. Below market wages and guaranteed to stay on the job for many years without the employer having to bother will things like annual raises, good work environments, and work life balance.