You'd be surprised. Even if you're aware of it, you may start noticing a post you like made be a high-karma person. Confirmation bia sets in, and very soon, your subconscious is engaged. This stuff was build that way by design.
Don't get me wrong, I get the little dopamine rush and enjoy getting points and stuff, but I look at the whole thing the same way as a high score board on a video game or something.
Now you made me curious about your opinion of karma on places like stack overflow.
I've never participated much in any of the stack overflow communities other than passively. I tried asking a question once that I hadn't seen on there but I got downvoted and told off so meh...I just stick to searching and passively reading mostly. I have thought of updating some older answers but they were usually locked and closed to discussion.
Thanks for sharing your perspective.