Your 30s is certainly not too late. It's not late to start a new career, or even to start your own business.
Here's some people who started whole new careers (i.e. businesses) in their 30s:
Travis Kalanick - Uber
Jack Ma - Alibaba
Reid Hoffman - LinkedIn
Sam Walton - Walmart
Cher Wang - HTC
Evan Williams - Twitter
If you're interested in switching to entrepreneurship, here's a guide on the 10 best books to read before starting a business. https://www.providecover.com/10-best-books-to-r...