It reminds me of google plus. Technically better than the existing top dog, but the forced migration and trying to bootstrap with a huge but only semi involved userbase let it fizzle soon after the start.

Has there ever been a successful case of bootstrapping a new social media product with an existing userbase? Like not just added features or merging two together.

Google+ was wildly successful in certain circles. Tabletop RPG design still hasn’t entirely recovered from its loss.

Google+ was successful from any real metric but it didn’t replace Facebook so it was axed.

Yes. WeChat bootstrapped off of QQ accounts, which were basically like Yahoo or MSN messenger + pages for desktop users.

Not sure how you define "technically better" but in any way I'd add "citation needed". G+ was kinda horrible with a couple good ideas and I think the lack of widespread adoption spoke for that.

It's not exactly new social media product, but Facebook did add messaging to their then Facebook app, build up usage of messaging itself (network effect within the user's friend list), and then split it off into its own Messenger app. They are sharing the same Facebook login through.

Well Facebook bootstrapped using the MySpace userbase.

I never used and would never use Threads for the same reason I never even considered Google+. It was DoA and I guess everyone could see it, even the people who were trying it. Such is the case with Threads.

I mean that morning when Zuck woke up and decided that a Threads a/c would need an Instagram a/c he must have seen on his daily astronomy calendar "Day of self-sabotage".