I just turned 32, and I've been thinking about things I wish I knew when I was 16. Here's the shortlist:
Products beat consulting: Zero marginal cost is amazing
When I was 16, I was happy to get paid $7/hour for working on computers. I loved computers, and $7 was more money than I really knew what do with. But it's one thing to make something for one person or one need. It is vastly more useful to create something for lots of people that can be used over and over again. When you can either create products that sell again, or you can sell your own time, always choose the former.
Learn or earn
You're always on one side or another of the learn vs. earn. Given the nature of equity and corporations, always know that owners reap the rewards and workers are transacting their time for money. But unless where you work is a co-op where profits are evenly distributed, you'll never extract the full amount of value that you create for the company. Always know whether at that moment you're learning or earning. If you're learning, then it's worth it. If you're not, you better be earning (e.g. being a founder, being a share holder). Otherwise you're just wasting time.
Human beings are mirrors
If you have good will towards others, others will have good will towards you. That's why it is better to assume people are fundamentally good, until there is evidence to the contrary. You'll be better to others, and then they'll in turn be better to you. In contrast, if you assumed most people had ill will towards you, you in turn would likely treat them in ways that would invite that. Life seems full of self-fulfilling prophecies like that.
These lessons I learned in just the last 2^4 years. I can only hope the next power of two will be as instructive and amazing as this one.