Philosopher Karl Popper defined the paradox in 1945 in The Open Society and Its Enemies Vol. 1.[1]
Less well known is the paradox of tolerance: Unlimited tolerance must lead to the disappearance of tolerance. If we extend unlimited tolerance even to those who are intolerant, if we are not prepared to defend a tolerant society against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them
https://en.wikipedia.org/wiki/Paradox_of_tolerance
https://www.youtube.com/watch?v=45VIj1_cr0U
https://en.wikipedia.org/wiki/Paradox_of_tolerance
https://www.youtube.com/watch?v=45VIj1_cr0U