Because good-looking people have perfect lives and unfaultable existence!

artwork by Robin Isley @theartidote

Research has shown that we (everyday folks) automatically assign favorable traits such as talent, kindness, honesty, and intelligence to good-looking individuals (for a review of this evidence, see Langlois et al., 2000). The irony is that “good-looking people" are aware that other people’s positive evaluations of them are not based on their actual traits and abilities are caused by a general attractiveness or "halo" 
― Robert B. Cialdini, Influence

Much like other human biases the 'Halo Effect' is a well documented phenomenon, the reasons are complex and instinctively embedded in our eyes, such as being visible, tangible, mystery plays a part and perhaps our own escapism or insecurities - we admire what we value because it might as well depict our longing or if there is a loose value attachment (talent, kindness, honesty and intelligence - all good value as opposed to shitty ones, controllable, constructive and reality based).

Nothing sums it up the way - a radio broadcaster described it on air the other day - He said that hyper social/affluent peeps from upper echelons of society including Tinseltown circles that are gorgeous and prohibitively hot are eleven out of ten times BORING AF. 

Because they don't have a personality, because they don't need and/or required to develop one for people to want to hang out or be around them. So they're a beneficiary of a human bias, but they've done nothing to be worthy or deserving and once the bias run out we're left with let down stories. Perhaps it was our flawed perception/judgment which is the let down instead of good looking people. There was an ad which said, asking beautiful people around beauty tips is like asking for financial advice from someone who just won the lottery.

On the flip side, I wonder what it's like to know you are being overvalued that you're not - imposter syndrome and self doubt will run high - Being preceived to have a perfect life and having no issues. Again, even if we mute/numb it by linking self worth and ego with it - that it might be skin deep but it's a fun ride till the skin wears off. It's still like having a beach house and a lot of people love to be around there, but they are there for the waves not your personality/skin deep features which is decaying every passing second. 

 
May be it's God's redistribution of wealth, looking at the documented correlation between looks and earnings data. The hot stuff ears around ~12% more income per annum compared to average looking peeps.

Some are born into kingdoms/artistocratic families and some with visual tools (easy on eyes) and some with usual accessories i.e. brain and brawn. Perhaps the answer is self acceptance with a commitment to self improvement!