"Nowadays you can buy golf balls at Wal- Mart that have been retrieved from ponds. I was on to a million-dollar idea way back then, but didn’t know it! I made thousands of dollars over the next couple of years selling lost golf balls."
What does the sentence (I was on to a million-dollar idea way back then...) mean?
Does he mean that he had the idea that would make him earn a million dollar but he didn't know?