Comment by JamesBarney

I think a lot of these posts aren't arguing "never build a side project to learn a new technology". I think they're arguing you should go into it eyes wide open, deciding if you're trying to learn new tech or build a side project. Because the first goal will interfere quite bit with the second goal. And more than a few devs have made the mistake of trying to start a new business on new tech and have blown their foot off.