[this_user]

It is a similar problem to YT. Coding the site would not be that hard, but running it at scale is. Moreover, it's expensive. That is what reddit has struggled with itself, because the platform doesn't monetise their users as heavily as Google or Meta, and has always had more open and laissez-faire approach.

The only way to launch a competitor that is profitable is by going the Google/Meta way, but then users will just stay on reddit. Otherwise you need deep pockets or lots of VC money, but why would they invest in reddit clone that will just end up in the same place that the original finds itself in?

As for the corporations, you need them and their ad money, unless you want to run a subscription model. But that doesn't work either, because the majority of users will just stick to the free sites if you try.