There's nothing wrong with un-publishing old stuff if it no longer reflects how you think, or if you feel it's not relevant anymore. You can always keep a private archive.
I think a lot of people think of blogs as "production-quality writing", which is natural because for part of the 2000s, blogging = money/recognition. That era is over, no matter how many people start (and later abandon) Substacks.
In general, writing/podcasting/making videos with the primary intent of directly monetizing them has pretty long odds. The recognition angle may be useful if it's connected to your day job and anyone cares if you have a public persona or not. It's been useful for me but you have to have the right expectations going in or you'll probably be disappointed.
I think a lot of people think of blogs as "production-quality writing", which is natural because for part of the 2000s, blogging = money/recognition. That era is over, no matter how many people start (and later abandon) Substacks.