The classic "tolerance of intolerance" thing (not sure if it fully counts as a paradox).

Basically this has been stuck in my mind ever since 2018 when I hear a friend of my aunt's teenage daughter answer the question "should we tolerate the intolerant" with "no, we should NOT tolerate intolerant" people.

I didn't think of this back then but, by definition, if you do not tolerate intolerant people, you are yourself intolerant, and therefore do not tolerate yourself, which I imagine could lead to some problems if your life goals are anything other than "self-loathing tortured artistic genius".

Related, the classic "I can tolerate everything except the outgroup" from Scott Alexander https://slatestarcodex.com/2014/09/30/i-can-tolerate-anythin...