Many times, I've seen arguments made like this: "I'd try Mastodon, but I already have Twitter followers", or "I'd like to use OSM, but Google Maps has better data for my city", or, in my case, "I'd like to use sr.ht, but GitHub has better discoverability".
Platforms for which popularity improves the utility of the service are skewed in favor of the incumbents. New platforms face a chicken-and-egg problem. You have to decide - will you help it, or exacerbate it? Those are the only two choices you have.
Don't let that cool new platform die in obscurity while you wait for it to become popular.