I find a lot of the smartest people I know are also the most depressed and have a lot of wasted potential they won't ever be able to put to good use.
Being good looking opens a lot, and I mean a lot of doors. Not just in being able to date or sleep with whomever you please, but in job offers and advancements and overall how people treat you. Imagine an almost cartoon-like world where as a good looking person everyone is always smiling at you, asking how you're doing, if you need anything, etc. You get through life pretty easy and can get away with a lot more than the average person can (being dumb, absent-minded, careless, even vulgar or rude/abusive toward others).
Then the inverse of being an ugly person where at best you're mostly ignored and just barely scrape by in life, and aren't actively discouraged, berated or bullied by others constantly. I feel like most ugly people are basically walking on eggshells because if they fuck up the hammer drops on them twice as hard because people aren't afraid to be a dick to an ugly person.
It's like the Halo Effect. People angelicize (dunno if it's a word, but opposite of demonize) everything a good looking person does, while often demonizing a lot of what an ugly person does. Good looking person is charming, romantic, interesting. Ugly person is awkward, creepy, annoying. Even when exhibiting the exact same behaviours.