Well for me there were several foundational beliefs, and once the last of those collapsed through research I was no longer able to believe in anything supernatural.
One of those beliefs, for example, was about the prophecies of the dead sea scrolls. It turned out that those scrolls were dated 200-300 years after the events that they "fortold", which is something I didn't learn for an embarrassingly long time. I thought if the prophecies were true, then the bible must be true. Turns out there's no real evidence of that.
I really started to look for evidence of anything supernatural, and always either found a lack of evidence, or discrediting evidence for all of those foundational beliefs.
I wanna take another stab at this question because I don't think I covered it. As far as leaving, there was no real big event. I just stopped going to meetings and my parents stopped asking if I was going to meetings. They still try to preach to me when I visit and I just kind of awkwardly sit there and let them talk. I'm categorized as "inactive", which means my family can still talk to me, as opposed to "disfellowshipped" or "disassociated" in which case they wouldn't be allowed to talk to me. I could write a letter to the congregation leaders renouncing the faith and become "disassociated" but I really don't have any personal need to do that.
If I could talk to my dad about it, who is much more reasonable than my mom, I would. But my mother would find out and it would absolutely crush her.
What was the trigger that made you drop it? Its a gradual thing for sure, but at some point, you get the guts to actually drop the religion. Was it a big event, or did you just build up enough courage to finally do it?