Here's what's astounding to me: scrolling through the responses here on HN shows an almost total focus on money and career. I read the piece and thought about life and personal ambition. That's kinda interesting.
Anyway, fwiw: I'm 47, living by the sea in the most beautiful bit of the UK, and running a successful micro business which works with non profits.
I've deliberately chosen a path over the last decade which is about family, and I say no to any business which would cause high levels of stress, no matter how lucrative. I only work with people I like. I say no to lots of work. I've deliberately taken the choice to not grow staff or move into an office, even though we have the financials and potential to do so.
Why? Because life is about more than work. I've got two teenage kids. I see them for hours every day (not 20 minutes which I read recently is the average US dad daily contact time with his kids). I get to surf with them, to eat with them, to be with my wife, to read, to play piano and do hobbies.
Do I put some money aside? Yes, a bit. Is it enough? Who knows, and who cares. I'll work until I'm 90 if I have to so I can continue to have this quality of life with my family and the environment around me.
I'm incredibly, incredibly lucky - there's no doubt I've had a great path through life so far. But if I'm able to offer advice now it appears I'm an old git (and yes, the speed with which life happens is as per the article, it's terrifying!) - it's this: live your life. Live it and be poor. Take every single chance you can to be with your friends and family. Say yes to work that makes you happy. If it doesn't, find something else. In your 20's you'll want to eat the world. Do it, while you have the energy and appetite, but know that when you get older your tastes are going to change. Slow down, and accept that most of the best things in life aren't work, aren't money, and don't require either to create meaning.
Be in your life.