It’s shiny, they advertise, put in a money to spread the word. And the onboarding process probably is way easier?! Also back when Mastodon was in the media, it wasn’t yet the right time. Now, especially with Musk, it is. And the attention is on Bluesky since that is newer and what’s hyped right now.
I wouldn’t know, I have a lot of adblockers etc. But it gets to me via word of mouth. And it’s been in the media a lot this year. Due to their business decisions, new approach, novelty… That’s something they did very well. They also took care building some hype and anticipation with their invite-only period. Mastodon has also been in the news. But that was yesterday’s news and I suppose everyone forgets yesterday’s news.