To answer the OP:
I became a Catholic as an infant because that’s what my mom was (my dad is non-religious). I left the faith in high school after being Confirmed, and I came back after having a powerful experience at Mass while away at college as a freshman. I stayed Catholic rather than look for “a church up the road” because it’s all I’ve ever known, and I didn’t know what I believed yet. I had hardly read the Bible in my life, so I started there. Then I found this place and had all of my “beginner questions” answered.
Since then (that was two years ago), I’ve been engaged in private study. Virtually everything I read these days is theological in nature. I read all 73 books of our Bible, and I’ve been reading up on Church history. “I was Catholic because I was raised Catholic. I am Catholic because of what I’ve found in the early Church.”
I accept infant baptism because of my understanding of Covenant theology (sound odd? It doesn’t anymore if you understand one key- though easy to miss- element of God’s covenants).
I accept the Eucharist because we understand Jesus’ death to be a sacrifice- and in Judaism, a sacrifice wasn’t unless it was eaten. (In other words, a sacrifice only occurs if you eat it)
I accept the priesthood because I accept the Eucharist (there’s no priests without a sacrifice. Likewise, a sacrifice requires priests).
I accept the Papacy partially because of Peter’s preeminence among the apostles in Scripture (but mostly because of his confession in Matthew 16, and what Jesus said to him afterward).
But for me, it ultimately all comes down to, what does the Church say?, and everything I know of the Catholic Church is in harmony with the early Church.