There’s a lot of “feel free to... {vote, leave, whatever}” in this thread but I just want to add there’s very little freedom in the American voting system. You’ve got two choices, sometimes no choice if you live in a “safe” district. Ya’ll need to get angry about not having 1 person 1 vote before angrily telling everyone else to use theirs.

In fact, most American voters live in "safe districts" today, and their number generally goes down over time. On the federal level, we currently have something like 350 districts that lean strongly towards one or the other party, and 80 that are actually competitive.

Those two (or one) choices are also voted on. You can vote in primaries.

AOC won the primary in a safe district against the 4th most powerful Democrat in the federal government.

She’s a black swan. Good for her and your democracy not being completely and utterly dead

It wasn't random. It was the result of a group devoted to winning primaries. They've had some success, starting the same year as (but not exclusively) with her. And continuing through this year.

She was the most prominent upset result, but that's because of how powerful who she defeated was. There isn't much room above what she did.