That's nonsense wrt invitation-only being the future. I can equally say that free speech is the future. For comparison, Reddit does very well without being invitation only.
reddit does okay from a profit standpoint. reddit does terribly from a bot or even a good community standpoint.
Reddit is literally the dead internet right now.
It's also not open access. You have to run an invisible tightrope so its algorithms won't automatically shadowban you and then you have to run a barely visible tightrope to get enough karma to not have your posts automatically removed from every subreddit.