Isn't there something better one could be doing?
He obviously built value for a lot of people. In addition I'm sure developed some very portable skills. Helping to curate a site that brings that many people joy? We should all be so lucky.
The idea that the rug could be pulled out is indeed a significant lesson, but it's frankly one that both sides of the coin need to learn. Platform sites that encourage users to invest in and create content for will suffer if that content isn't taken good care of, in the long haul.
Besides: your company? It'll probably fail before having more than a couple thousand customers. This page? It certainly had more people interested than that!
So it's not just a viable hobby, but one at which the author was relatively successful.
Same frame of mind I think, slightly different way of expressing it. :P