On average, the US has a lot of things going for it for a young software professional if he or she can navigate the immigration maze and is reasonably lucky. Might not be for everyone but for the average person, getting a cushy job in a large company might be better for stability and long term satisfaction that risking it on an attempt to create a unicorn (which is rarely successful).
It's not a bad thing imo since families should strive to improve their situation with every generation, but it's important to highlight that rags-to-riches stories are extremely rare.
There are probably many who also got their visa rejected and were stuck with huge loans for their studies and an Indian salary, or had to move to EU/CANZUK countries as a second option.
Upper middle class covers a lot of commonplace jobs like dentists, accountants, engineers, etc.
Also you're leaving out lots of people that do come from even more humble origins like Steve Jobs, Oprah, Jay Z, Soros, etc.