Because they feel if they have everything and lack nothing they will be happy. Little do they know that once you get used to always getting and accumulating more and more money/things you become addicted to that feeling and you just never stop and eventually you hit a point where there is NOTHING else you could possibly want.
I have a friend who came from humble beginnings. His family is from Afghanistan and he grew up pretty poor (as most immigrants do until they can save a up little and move forward), I've known him since we were kids because we grew up in the same building (we were poor too). There were times my parents would help his with food and vice versa, or we would share toys..you know stuff like that, poor people things lol.
There was time when we hit about 10 years of age and this kid Nick had gotten some new Nikes, my buddy was so into the shoes he even asked Nick if he could try them on. I guess that night he had begged his parents to buy him some new shoes, which was impossible at the time for them. He ranted to me how he hated not being to buy anything and watch other kids grow up having everything and us having nothing and he made promises to himself that one day he will be rich and never will he have to want anything because he will have it all.
Well now we're 27 and he's VERY successful, I'm talking millionaire. He owns many franchises, houses, agencies, cars, boats, even his own plane. Once he had all of that he mentioned to me there was nothing left for him, so he thought maybe he was "craving" settling down and starting a family. Which he did....3 times (no kids though), all times he was STILL miserable, he then turned into a man whore, one beautiful woman after the other. He ranted to me again about how he can't figure out what it is he needs but he just felt he NEEDS to get somethings add to what ever it is he is missing (if that makes sense lol). He started drinking, everyday a little more and more, then he started messing with drugs. I started seeing him more and more rarely because he was always too high on something to really talk. Despite me begging him to get help he wouldn't listen to me, because he didn't feel the need too since he could literally just lay in bed forever and he'd still be making money and it wouldn't affect him.
I haven't seen him since October, which was at a friends birthday party at the strippers. He was there, all alone in a corner, super dressed up, barely able to hold his head up and just throwing money at the girl standing in front of him. When I said hi he gave me a long hug and offered me money to sleep with him, because apparently "every girl has a price and I can afford it all", I was extremely insulted and creeped out all at once.
It broke my heart truly because I can only remember him as such a sweet guy, almost like the older brother I always wanted. He would take care of me when people were mean, or share his lunches with me and when he started making money he helped me get on my feet during tough times. I miss him so much and it makes me mad that he changed because of his excess of money.
This turned into a rant but damn does it ever feel good to tell someone about how I'm taking it :(