This isn't the "what radicalized you" line of questioning. I always read those as the last straw. I'm more interested in your first steps.
I know everyone's journey is different.
Mine was realizing that despite being a complete asshole, I give a fuck about everyone.
My grandpa was talking shit about "communists" and I asked my mom what that word meant. She said it's people who think everyone should be equal. That sounded pretty cool to me so I asked what was wrong with that lol. Then I got the standard bullshit about "everyone making the same despite hard work", "failed every time", "human nature", etc. which I believed, but there was always a little part of my brain that thought it was a cool idea.
Another thing was seeing old abandoned buildings with the doors and windows bricked up and cemented over. I asked why they did that and someone told me it was to keep the "homeless people and junkies" out. I thought that was messed up and didn't understand why it was considered normal.
It's crazy how we raise children to value sharing, selflessness, respect and helping others, and then expect them to forget all that because it's "against human nature"