It's the paradox of intolerance because it's a paradox, i.e. a logical contradiction. If you are tolerant to intolerant views, they will gain power and censor your tolerant speech. But on the other hand, if you are intolerant towards intolerant views and censor them, then it's ok for someone else to censor YOU for being intolerant.

You can go a step farther and say that "tolerance towards intolerance leads to intolerance, therefore we should be intolerant towards tolerance in the first place!" It's a paradox for a reason, and no high-minded solutions of "intolerance in the name of tolerance" are able to sidestep its implications.

There are two conclusions that I personally draw from it. The first is that intolerance/tolerance is not a binary, is not easily definable, and therefore there is no clear standard for what speech is right to censor and which is not. i.e. the paradox is unsolvable. The second is that "tolerance" and "intolerance" are not great words to describe the dynamics at play, they carry extra nuance that is not helpful.

(if you can't tell, I'm not a fan of the paradox of tolerance)