> Who is the most famous tech founder who was 45 or older when they founded their first company?

This is a straw man fallacy. I think you're conflating the definition of "successful startup" with a cohort of "famous tech" founders, which has some merit (lower age yields higher risk).

The broader definition of "successful startup" is more about "fast growing" or "economic impact". The emphasis is on founders of “growth oriented” firms that can have large economic impacts and are often associated with driving increasing standard of living.

An MIT Sloan study found the mean founder age for the 1 in 1,000 fastest growing companies is 45.0.

http://mitsloan.mit.edu/uploadedFilesV9/180325%20Age%20and%2...