Why do we seek approval/validation?

Sense of belonging, fitting in someplace.

We want to feel understood and accepted.

Human nature.

Because if you didn't have it 10000 years ago you had 2 possibilities.

If you was lucky you'd starve to death

If you was unlucky you were a snack for kitteh kat.

This is also why we fear public speaking, and hate rejection.

Everyone wants to feel accepted but some love themselves to a nauseating level.

we dont want to be alone, we want connection, acceptance, we want our souls echo to reverberate off something, instead of being lost to the emptiness. for many other people are like a mirror, without them theyd never know who they are or what they are like.

Evolutivelly, cos we are mammals (midbrain).
Cos we are a social species.
Cos all that noisy mantras about the "selfwhatever" and that the value and meaning are provided by "the inside self" are as empty as a ten years nut.

Humans are very self centered and it can feed the ego. It can also become addictive and social media promotes that

It's crucial to development in childhood, some people just don't grow out of seeking it.

As has been said, it's human nature. I just wish I knew how to stop doing it.

Lack of confidence in one's self

Comfort