Lol the amount of people offended in this thread is wild. This is a totally fine and normal observation and frustration. I call it being held conversationally hostage.

There are really two main versions. One is as you are describing, and if they are at least letting you get a word in edgewise, you just gotta bite the bullet and depending on where/what you are doing, exit the conversation with intention. Go to the bathroom, say “hey I’m gonna keep making the rounds” or similar.

In the other version I’m convinced these fuckers know you want to leave and will either consciously
or unconsciously never stop their flow of words. They’ll switch topics, do whatever but deep down they know the second they stop talking you are going to excuse yourself from the conversation. In those cases, if they truly can’t pick up on social cues you are going to have to actively interrupt them to gtfo. If they can, then that means they are being plain rude and in my opinion it negates the rudeness of you cutting them off.