Your argument is based on a false assumption: that hiring is a zero sum game. That there's a fixed number of jobs, and every foreign worker hired means one less job for local workers.
Of course, that's not true at all. When an immigrant comes here, they work, live, and shop here. They perform valuable work that adds goods or services to the economy. They support other businesses that they shop at. They pay taxes that support public services. In other words, they create jobs.
Now, that leaves an important question: do immigrants lead to a net increase or decrease in jobs available to local workers? That is, do immigrants on average create more or less than one job each? That has to be answered with evidence. The available evidence is complicated, but much of it indicates that they create a net increase in jobs. At any rate, you can't just cite "bizzaro logic" and dismiss the question. If your logic conflicts with the evidence, then your logic is wrong.
How is it possible that such a country is producing such huge numbers of "highly skilled workers"?
Wow. Do I really even need to respond to that question? I'm amazed you could even ask it.
Ok. India has a population of roughly 1.3 billion people. If only 10% of them are well educated and highly skilled, that's more people than the entire population of Japan, Germany, South Korea, or many other countries with huge tech industries. In fact, 10% of India's population is larger than the population of all but eight other countries.
India has a lot of people in terrible poverty, but also a lot of people who are highly skilled and educated. And because it's such an amazingly large country, the numbers of both are enormous compared to almost any other country in the world.