Thanks for the question.
Because it shows me that if devaluating another person is my strategy in feeling better than I may be a winner of a debate but a loser of a relation (and my "face").
Devaluation actually is hurting my self esteem. I made that experience with people after fighting with them. When I said something mean I afterwards felt utterly bad. The satisfaction for having expressed something devaluating lasted exactly thirty or so seconds while adrenaline was still in my blood. Cooling down, I realized that the only one who I was fighting with I was myself. Even thinking bad of someone takes me down and leaves me dissatisfied - how about you?
I made the experience that finding consensus and respect makes my relationships richer. In the long run I don't have to spend so much energy in my self-esteem, it will come more naturally when I treat others good. Within this I still can remain critical and active.
... Not easy to practice, though. I am still falling into old patterns and habits.
To lose someone into one becoming an enemy which also I would have had a chance to befriend myself with is a loss which is not necessary. We are all also contributing to the big picture, don't we?