Ask HN: Why can't India produce homegrown Tech Product firms?

I am curious why India does not have good product companies with global reach like TWTR, Slack, FB etc. We have a lot of talent (large number of CS grads), but most people end up in IT services or doing maintenance/Dev work for large companies like ORCL, AMZN.

Most of the so called Indian "Unicorns" Like Ola and Flipkart are rip-offs of successful US companies.

What would it take to build billion dollar product companies in India?