Sure, it may overestimate the exact count, but that doesn't change the fact that tens of millions of real people have downloaded Bluesky and signed up.
Right now, Bluesky has one large community, which is already great for some people but not most people. Once Bluesky adds Communities, new communities can form, making it interesting to the other 90% of people who were excited initially and then turned off by it being "one note".
I think your association with Blueksy is painting a rosier picture for yourself than reality portends. Do you know how many of those accounts never added a profile picture or even liked a single post? Do you think people are likely to reactivate to something they checked out once and has only shrunk since? Can ActivityPub/Mastodon add some new feature that will reactivate all the people who tried that out and moved on?
If you'd like to crawl the network to get real data, I built this a while ago https://github.com/verdverm/atmunge (it will take a few days to get sufficient data to do analysis, due to rate-limits)
Certainly Bluesky has stats about mobile app installs / usage. If they were good, they would be sharing those instead of the /users/accounts/ number that feels good but hides the reality. The first step (imo) would be to stop trying to deny reality and start asking why it is the reality. Only then can corrections be made. I don't think the core issues are technical, a missing feature, or a social media modality that was supposed to be built in the atmosphere. (other than my strongly held opinion that public-by-default was the wrong choice and bolting on permissioned spaces now is not a right answer)
I'm personally waiting on the next attempt that learns from AP/AT/Nostr, but makes privacy first core. I think it will be a few years still. Right now more people are shunning social media across the board, it's all so toxic and polarizing regardless of modality and where you use it.
I'm not claiming to know what reality portends, but I do think my guess is about as good as anyone's.
Bluesky did something ActivityPub/Mastodon never did, which is reach a mainstream audience of non-technical people. But its growth has been severely limited for one reason: the network is niche and uninteresting to most people.
Communities are a potential solution to this problem. If they work, it is plausible that tens of millions of users reactivate and, eventually, hundreds of millions of people join the network.