What is the purpose ?

What is the purpose of everything that happens around and everything that i do ? I have some 60-70 years, i study something which will be obsolete in some 100 years, so is it like am just a brick on which a wall is made, is it like i may chose to be a part of the wall or to lie in dust and be of no use. But even if i chose to be a part, what do i gain - that wall is going to crumble some day coz thats the cycle of life, so why do i build it in the first place. I earn something which is all man made, isnt it like playing it a game of cards in which i score and at the end of the game i get up and go and i realise i gained nothing but lost all the time that i had. If i stop today and look back at what i did ?..............................
i had a nice childhood, a good student life, bagged a decent job and salary, i still aspire to earn more and earn what - money !!, so that i get all comfort ? But thats a localised posession coz drop me on himalayas and that money is of no use to me, so what did i gain in real, nothing.. did i waste all these years then ? But what do i do to gain something which will be there for me here and at himalays and everywhere and for always and what is that thing ? I dont know and till i dont know i do what i see around, i work to earn more , even though i know its fake but i still do coz i have no other option. But someday i would like to know "THE PURPOSE"