MITx had a profound impact on my life when the platform launched in 2011. Ditto edX.org in 2012. At the time, I was a college dropout. My job history looked like: self-employed, Starbucks, and a bunch of catering per diem gigs. I didn't know what a "software engineer" did, although I had a vague desire to make video games (but no idea how). I was technical enough to install WordPress with Cpanel and resell hosting to…
The millions of people who took a similar route and didn't become millionaires would like to point out that this story is exceptional, as in well above average, extraordinary and very uncommon. Congrats on thus far making the most of your life and abilities, though.
I didn't mean to imply this is a repeatable process. I know that I've been fortunate, and in my mind that chain of luck begins with stumbling upon the MITx courses. The OP asked about courses that impacted your life, so my story felt appropriate.