Here's what you know only a little later in life: choices have long tails. Consequences last, and create further consequences, bad and good. Just as possibilities for real life narrow, you find yourself living evermore with the shades of lives-that-might-have-been, with the multiple possible universes of what might have been proliferating spontaneously from the twin fuels of your imagination and regret. Increasingly, you have one foot in, and one foot out, of the 'here' and 'now,' and you find yourself time traveling, visiting the pluralverse of all your incipient and abortive selves.
Young people have no idea this splintering of their univocal reality is coming. That's their tell, beneath all the witty irony, and apparent early wisdom. It's also their birthright, and as such, it's enviable.