Reddit never owed me anything, never spent any money and was paid back for the time invested. Might spend 5 minutes per week on it now. Plenty of people are trying to make a better Reddit, nobody has targeted them with unfair competition.
Of course, the huge downside is networking effects and you now in the 2020s have to compete against "free" services. It shouldn't be such a hump to overcome if you appeal to the right crowd, but you also need to somehow appeal to the power users who will ultimately get your site off the ground. And those are never easy to find.
I do not understand people who volunteer unpaid labor and then complain bitterly about it.
I’d be more worried about those that don’t complain.
Well, let's say you helped someone on Reddit.
What you were intending to do is to share your life experience with someone, making their, and maybe probably someone else's life meaningfully easier/save them some time. And, hopefully, someone will treat you the same way in return.
What you also have done is contributed said part of your life experience towards making some meaninglessly rich guy even richer, and who will enshittify the platform you presumably enjoy using in return, so that he can make pennies on top of the follar he already earns.
If there's a better platform for giving you what you want, I'm sure you'd leave Reddit and never look back. If this platform you're imaging doesn't exist, how do you know it even could ever exist?