I actually dislike this.
The narrative that your value comes from external validation is one you see a lot.
But a person shouldn’t be told that “you are beautiful based on another persons perspective” because that cuts both ways.
If you tell them this, it can easily be flipped around to say “okay but theres 10 million people on the internet who would love to call you ugly so thats 10 million to 1”
Instead, the only person whos opinion on your body that matters is YOU, and thats it.
And Ill keep banging that drum.
If I have a daughter, Im gonna tell her this all the time, “tell anyone who tries to convince you that beauty is in the eye of the beholder, that the beholder outta keep their fuckin opinions to themself”
Even though I agree that external validation shouldn’t be relied on, and your own opinion of yourself is the most important, that’s still really hard to do when you don’t like how you look.
A different comic that connected to me a little more was this one:

Where just because I don’t like the way I look, doesn’t mean I’m ugly. Someone else may like just as I am, so the important thing for me is to be healthy and happy with myself, even if I don’t like how I look
… I’m realizing I’m mostly just rewording what you said, but I wanted to share the comic in case it helps someone else see another perspective :D
Like many other mentioned, welcome to human psyche, where your PoV does not have to match the PoV of others. Some need awareness that external validation exists. Some need awareness that while it exists, it does not have to be more important than your own view. There is no cookie-cutter option, sadly.
Best case scenario is - teach a kid that their view is valid and true, while also pointing out that people have so varied tastes that she will always be considered attractive and we have no “hard” definition of beaty - it’s all subjective, both within and without.
Some need awareness that external validation exists
Hard disagree, external validation is not a fundamental need.
Any perception that it is, is an internalized mental blocker (likely due to countless years of social conditioning)
Your cage is made of out of sticks.

