Comment by csb6

There is no harm in building a compiler and designing a language as a hobby. It is gratifying to build something and see it work, and it is often interesting to hear about other people’s projects.

The problem comes when designers have delusions of grandeur about their language/compiler. There are lots of people like this on programming language forums who drive themselves nuts because they don’t realize that languages become popular due to platform exclusivity/marketing or due to word of mouth around a readily available implementation that offers something unique. Most hobby languages/compilers are not that different from existing ones so this rarely happens. And the people who create languages are rarely good at building communities because they usually lack social skills (and they tend to be a little manic/defensive about their creations).