You probably gave as good a chance as any, maybe higher at MIT and Caltech with the math experience. It’s still a long shot for anyone.
If the above is true though, why choose any of them. Your current success is very valid evidence of the likelihood of success in the future no matter where you go. There are lots of schools where you’d get a good education and job potential and lots of aid. Don’t put your family in distress.
That said, economics/CS from MIT is pretty powerful. You could pay them back a portion of it from your wages. That would leave you in a hole though. Good luck!