About 5 years ago when I was still in high school I found $500 in a derelict paypal account that had been locked. Having finally gotten a debit card I was able to unlock the paypal account by linking my bank account. I decided to immediately chuck $350 of it at coursera (although it could've been a similar product I can't remember). I wanted to become a successful mobile app developer and self-learning seemed the best way to go.
Long story short the courses I happened to pick were of low quality and never completed. Four years later I still cringe when I hear the word eclipse (even though I'm getting into mobile development now after a few years in webdev land). While I'm sure there are a number of very good courses, and quite a few people capable of completing them and benefiting from them in their lives, I believe I was at the time not only the prime demographic for the product but also in the majority of their users.
TLDR; you can make any learning opportunity beneficial. Is courser and similar products worth the effort to make productive? Maybe, maybe not. There are other alternatives that should always be researched.