Liars can't say I'm a liar! Because their are liars.

But everybody can say "I don't lie". There is no paradox there.

My pov is that when there is a paradox, it means that the current model/system has reached its limits, and we need a new one more general, like gravity and relativity.

Did you know that the infinite sum of 1 is equal to -1

(1+1+1+... = -1) ? This is a paradox