no matter how much money i would make, you will never see me flying first / business class before i'm 40

you can use the funds in like 1000 more productive ways than buying comfort for a few hours

a cost of one first class flight can buy you a year of workouts with a personal trainer which will delay the necessity for sitting in the first class for another 5 years

pure destruction of capital

if you lose a day to recoup/recover from fatigue or jet lag, the cost is quite worthwhile.

time is precious.