75 million supporters will create a lot of critical mass.
He doesn't have "75 million supporters."
Remember that a good sized chunk of those supporters didn't support him; they just opposed the Democrat. The number of true-blue, die-hard supporters of Trump himself is probably closer to the 14 million who voted for him in the 2016 primaries. Let's say 20 million, just to factor in any non-Republicans.
I'm just failing to see here what a Trump social network is going to appeal to. How much of that core is going to bother with another social media account? If this is just going to be a vehicle for Donald Trump to put out what otherwise would be going into tweets... that's not really social media at all, that's just a blog.
The reason Parler was starting to take off before it got kneecapped was it offered something that a sizable chunk of social media users were looking for: posts in chronological order (instead of an algorithm) and not interfered with by biased "fact checkers." I was seeing people I know who were only mildly political signing up for Parler. It was on its way to building that critical mass I've been talking about.
Will Trump's "social network" offer that? Probably not. If it's going to be a top-down model, it poses the same problems and complaints that we have with current social media, just in a different flavor.
By the way, I'm just as skeptical of the Attention Hogg's pillow company as I am with this. So it's not just the person himself.