19+40=59
What would a sixty year-old do with a million bucks?
Blow it on a souped up vette and drive on real petrol while you still can. They are probably going to run out of oil in 40 years and we will be all running on solar powered scooters...
After all, you only live once and the age of 19 is probably the sweetest time of your life.
So yeah, you'd be a millionaire surrounded by five 20 y-o swimsuit models but let's face it, by then you'd be pretty harmless compared to what you are now
But really, if you asked me, I would invest it in land but not in the USA - where there's plenty of it - but somewhere in the center of a European capital, maybe in the east if you only have 50k.
Your other option is education. Maybe go to Switzerland or Germany so you'd have that "edge" over the people who study in the USA (in some areas, it is helpful to have a more diverse background). You'd have lot's of fun, meet new cultures etc... You'd probably have to work a little to support yourself.
All said, 50k aren't going to let you hit the sofa for the rest of your life but it's a step forward, probably worth a whole year of your life (as in, you are relatively more advanced than people of your age who did not receive 50k).