I've known people who go back and forth on the lib/leftist barrier. One thing is a lot of them don't see a distinction, just that we use different words or we're scary because we say positive things about North Korea. I know a girl who has acab tattooed on her shoulder and Kamala Harris on her leg. She does not see a contradiction at all. She goes back and forth between calling herself a socialist and a liberal, because those two words don't mean anything distinct to her. The vast majority of Americans say leftist, Democrat, socialist, liberal, and communist to mean the same thing, including liberals.

I think maybe most Americans define themselves entirely by the boundaries of electoral politics and voting, but more broadly they define themselves as media consumers. They like particular personalities and responses to recent events, they don't care about structured coherent worldviews. The personalities and the responses are the ideology.

What finally tips it most of the time is a frustration with electoral politics and then reading theory. I know that sounds like an excuse, but it's all I've ever experienced. Gotta read and re-educate yourself. The libs who get engrossed in theory and become leftists stay that way. They become more involved in wider leftist movements and usually become more coherent over time. The libs who don't read theory but have more vague leftist sympathies will go back and forth, they'll primarily follow youtube or twitch personalities, they'll have weird idiosyncratic views, and the most important part, they'll snap immediately back into obedient voters for Democrats or maybe Republicans when there's an election. (note: having very close leftist friends or involvement in an org is often a good enough substitute for reading theory directly)