Especially if these users can share content, then you need to do moderation and hooo boy, you don't want to do that.
Why was this such a disastrous choice? I enjoyed having the site and with the exception of a couple of heated arguments in the comments, and spam, it was never a concern at all. Even the spam was very minor inconvenience since the filters caught pretty much all of it.
Many of my friends walso ran blogs in the late 2000s to early 2010s and the majority were smaller and had zero arguments in the comments and less spam as well. Just a comment or two on the occasional post.
The blog was the 2nd largest in its niche and lead to me making a TON of friends, one of whom I was later best man for at his wedding. I also ended up getting sweat equity in a business and learning a ton due to that blog. Moderating comments was little to no burden and even if its traffic were 10x more, moderation would still have been a trivial task.
It was a huge success in terms of ROI from my perspective. Having accounts and user-generated content on that site wasn't "betting on myself not to succeed". It enriched my life.