isn't it obvious that voting for the "lesser evil" just inevitably trends towards the greater evil over time? .

What's obvious is that multiple election cycles of non-participation lead to people who want the greater evil winning the vote more often.

It is not a successful strategy at mitigating harm

Counterpoint: literally any of the things that happened under Trump that Hillary almost certainly wouldn't have done.

Like nominating three of the judges that overturned roe

We've been down that road before

What doesn't happen is non-participation leading to the abolishion of America's two party system.