In reality why would you?
The same reason guys gotta have faster cars...
Bragging rights.
Oh look at me, my shite hole country just spent 5% and counting of our GDP on the tallest building ever!!!
But the curtain wall insulation might have some minor fire issues; enjoy it while you can.
I guess.
I would rather the world's most extensive botanical gardens. Useful, beautiful, attracting research and tourism to my country. Make sure my name was remembered for generations.
Probably cheaper as well.
Means I could have that really fast car too. :)