I agree with others that it's about perception.
Personally I'd HATE to be married, I'm asexual and do not want a relationship of any kind. Sadly some people assume I need/want a partner and am therefore pitied for it (much to my anger)!
As for beauty. I place very little value on being 'beautiful' (which is subjective anyway). In fact it occured to me a short while ago that all the fucking about with hair (dying/colouring/cutting/washing/straightening/drying ...) is so fucking pointless, what for? just so it can look 'nice' - it's just dead cells. So it's gone. I shaved it off and am far happier for it.
As for high paying jobs ... not everyone wants one. Some people are happier doing lower paid jobs for less stress or because they feel they are doing something worthwhile or close to their heart ie teaching/nursing. Money is everything to many people.
As for DCs. Why plural? Why any? I have one and am perfectly happy with just sticking with one. Some people choose to have none and are equally happy with their choice. Why assume that children = having it all?
Nice houses, what do you mean by that? Large? Expensive? Again it's not what everyone strives for. Some are very happy in a small cottage, a flat or bungalow. Some prefer renting and others prefer to buy.
Right now I'm the happiest I've ever been. Mostly because I am so grateful for every little thing I have. It may not be a vast amount to many people but what I have would be envied by millions (if not billions) across the world who lack the basics such as clean water, food, shelter, warmth... to those people almost everyone in the UK 'has it all'.