Extradition is 10 order of magnitude harder, even for the US legal system. Plus, he'll have enough time to figure out another country where extraditing him is just not worth it anymore.
Not really. As a local, I can get by without any aadhaar. He had $1.5m in bank, he could have started his parallel government, or probably for $15m but the fact is that even if you're doing everything by law you don't need aadhaar in India.
What would they offer to make it worthwhile? It's not like the US is holding Indian nationals in detainment whom the Indian Government would be willing to scour the country to find someone to exchange for release.
Perhaps they would for a violent criminal or terrorist, but it certainly seems unlikely for a relatively small-time white collar criminal. The fraud totaled $1.5M, this guy isn't exactly Bernie Madoff. Surely the US would not expect the Indian Government to spend multiple millions in operational and resource costs to locate, capture, and extradite a nonviolent criminal who made $1.5M illegally.
Could be lots of things more or less public and unrelated. One more diplomatic visa, help locating/finding/extraditing an India national from U.S., a little help for a contract... Countries have a lot of "diplomatic" incentives they can use for situations like that. And sometimes it is totally worth spending 10x the fraud amount if what you want to do is an example which could well be the case here.