should I acknowledge the possibility that they are just happy the way they are

They probably are. Also, even if hypothetically becoming super rational should be an improvement for everyone, your ability to change them is limited, and it's uncertain whether that degree of change you could realistically achieve would be an improvement.

Unless you have superior manipulation skills, I believe it is extremely difficult to change people, if they don't want to. You push; they welcome the challenge and push hard in the opposite direction. Unfortunately, defending your own opinion, however stupid it is, is a favorite hobby of too many otherwise intelligent people. It could be a very frustrating experience for you, and an enjoyment for them.

At least my experiments in this area seem hugely negative. If people don't want to be rational, you are just giving them more clever arguments they can use in debates.

I hate to admit it, but "people never change" seems to be a very good heuristic, even if it is not literally true. (I hate it because of the outside view it provides for my own attempts at self-improvement. That's why I usually say "people never change unless they want to", but the problem is, wanting to change, and declaring that you want to change, are two different things.)

Also, I noticed that when you are trying to change, many people around you get anxious and try to bring you back to the "old you". If you want to change your own behavior, it is easier with completely new people, who don't know the "old you", and accept your new behavior as your standard one.