My story is a bit different. I've made a conscious choice over the years to maintain a user PoV, by being a tester, tech ethicist and evangelist, rather than a software dev or server admin. So AP kind of came to me, because I was already using the fediverse when it came into being. As it happens, I shifted from an EU-based GNU social service that shut down, to a locally run Mastodon service, around the same time it was adding AP support on top of its existing OStatus federation.
But to answer the deeper question about what drew me to the fediverse, what @rimu1 said; network effects.
I've started and supported a lot of anti-corporate online projects over the years. Getting a critical mass of people to create yet another account was always a major obstacle. I could see the benefits of an open federation of disparate services in email, and to a lesser extent Jabber (XMPP). So as soon as I saw projects like Identi.ca and Diaspora applying that concept to social media, I could see the potential.
After more than a decade of pushing this concept uphill with a pointed stick, it's very exciting to see it start to take off in the wider open source dev world, and beyond