@maegul have there been any active user numbers on bsky? Mastodon's historical retention is < 15% so there are < 1M MAU today (not counting the broadly-defederaed "bad fedi" instances). Bluesky started invite-only which makes it easier to have a higher retention rate and it's newer so it wouldn't surprise me if it's bigger than Mastodon already or at least fairly close.
To me it's not so much a reason to dump on #Mastodon or the #fediverse, as an indication that the opportunity that Mastodon didn't take advantage of is still there. Bluesky hasn't addressed their moderation problems and so it's going to be very bumpy when they open it up, and also they haven't really started to federate and there are likely to be bumps there as well. They've got some good things as well, there's a lot the fediverse can learn from BlackSky, and it's not an either-or thing. https://privacy.thenexus.today/work-together-with-metas-fediverses-and-bluesky/ talks about some ways the fediverse and the Bluesky/ATProto world can work together.