I do not understand how your joke works.

If you genuienly enjoy antisociality as a norm, because you tend to be introverted, then you just like Seattle because of that.

You would then not be joking, in the sense of sarcastically saying you enjoy something you don’t actually enjoy.

‘I knew I liked Seattle for a reason’ is then just the same as saying ‘Yup, I’m also anti social and I love it here’.

The ‘joke’ isn’t that you actually don’t like Seattle’s social norms and were being sarcastic, because you just said you’re introverted.

I honestly do not understand how this is a joke.

Is… just using the pithy/vague phrasing… in and of itself… the joke?