If the activity has enough value on its own to be worthwhile without immediate monetary reward, then it's a good bet there's something valuable about your activity that will ultimately be recognized by the market.
Where is the evidence for that? Where are the broad data that looks at what has been done over, say, the last 20 years and examines what has been recognized by the market and what has not?
You can't just look at things that we now know to be successful, you have to (some how, if even possible) look at what was done and never became more than a hobby.
That's a good point. And in that respect, my comment and the blog post are fluff since they're not backed up by any research. And I think I overstated my point in the quote you selected.
But I think you can research it by looking at popular languages/libraries/technologies and who invented them for fun and their impact on the market. Yes, it's false to say that everything that's a hobby now is serious business in 10 years. The article limits it to very smart people. I'd limit it further to very smart and lucky people, like Linus for instance.
Where is the evidence for that? Where are the broad data that looks at what has been done over, say, the last 20 years and examines what has been recognized by the market and what has not?
You can't just look at things that we now know to be successful, you have to (some how, if even possible) look at what was done and never became more than a hobby.