Well, Its all about the THRILL of the CHASE.
Human beings like chase. They like to run after things that are out of their reach. There is a sense of accomplishment in that. There is a sense of victory and ego involved in it and plus the adage "You dont get what you want and you dont need what you get."
So coming back to the thrill of the chase. It's true. Till the time the thing is out of reach we go all guns to get it by hook or by crook. There is no stopping even if there is an option of getting something which is sure we still want to go after what is out of reach. You know its not possible. You know its immensely difficult but still you want to go at it till you get it.
Okay. Fine. You strive hard. You put your several years hard work behind it and finally by god's grace you do actually manage to get it. That's it. Game Over. Thrill of the chase is gone. It's fizzed out.
And as soon as the thrill is gone you realize the value of whatever you wanted is gone down too. You no longer want it. You no longer desire it. Something that was keeping you alive , it was your whole n sole aim to achieve it once you are done realizing the dream it feels the purpose is served and suddenly the thrill is gone.
The very same thing that you wanted now that you have it you no longer need it. You start taking it for granted once its yours and yours only. Because now there is no chasing it no adventure in it. And you again stumble upon something to chase for and the vicious circle of discontent continues.
Thrill of the chase is true in so many cases. Take live examples from your life itself.

Take them for granted. Go for greener pastures. Chase over. Game over. Relationship over.
Be it the company that you've been chasing for. You spend sleepless nights over it. Pray that you get the job and then there will be nothing else that you want from life.You finally get it. Game over. Thrill gone.
Go for greener pastures.

Be it the new phone/new bike/ a car you've been wanting it for ages. You wait eagerly. You strive hard to realize it. Its here. 1st day - love it . 2nd - like it. 3rd - enjoy it. 4th - bored of it.
Saturation comes everywhere. I got this forward from a friend which makes so much sense
" The irony of life is. The more you center your life around a person the more unattractive you become to that person."
It is so true and not only relating to people. But things. Every time you need some space. You need the excitement and thrill and enthusiasm to be alive and kicking. Anything in excess is bad and hence unattractive and enough because the thrill is not there.
So guys. Try and keep the thrill alive and try and value things even when they are yours because once they are gone its going to hurt and the harsh truth is it wont come back no matter how hard you chase for it.