scratch that -- i contribute a little by traveling to the us every once in a while (on vacations).
and even that visa, business/vacation was a big pain in the ass to get because for the us gov't i was going to stay in the us forever and ever because i happen to do work for american companies. i had to show the us gov't a ton of documents (from my marriage certificate to my tax returns and bank statements) to prove that not only i lived here but i also would go back.
and you know what the guy that was interviewing me said at the end of the visa interview? "i'm going to trust you". even after showing a ton of documents, it came to that -- a guy trusting me or not.
(btw, my wife also got her visa but it was way easier. she basically showed my passport with my visa and entry stamps and they said "ok!")
(btw 2: i was never more scared in my life than when i went to us for the first time. the border control point inside the airport was just insane, it felt like i was going to get arrested and deported at any time. there, i also had to provide a good reason for coming into the us + show the border control office my plane tickets, hotel reservation, money i had with me, credit card statement... otherwise i would get deported).
However, I'd argue you're still a net gain for the US, because your work - the value derived from it - is very likely quite a lot more valuable than what you're charging for it. In tech, often worker input is worth several times what they're paid for it. You're making a valuable net contribution to the US economy.
Not as much of a net gain as it would be if you were here also paying taxes.
So you're actually still cheaper for those employers than having an employee in the United States; ergo, you're undercutting American workers.