I don’t really understand ultras. They seem to see themselves as being the farthest left you can get while being the stereotypical armchair leftists that talk revolution and do nothing outside of that.

These aren't as contradictory as you might think. They claim to be the "most left" because they want to deny the existence of actual leftist movements, because they want to remain in their comfortable armchair and protect their ego. They are leftists to feel good about themselves, not to actually improve things.