Bill Gates and Mark Zuckerberg have had several widely-publicized meetings, so there have been no doubt a few private occasions where Gates has shared his personal experience with his younger counterpart. Here's how I imagine that conversation going:
"Kid, there are three things you ought to know:"
1. Computers won't solve the world's problems.
"About twenty years ago, I was sure that it would make the world a better place if we got computers into the hands of as many people as possible. I even wrote a book about it.
"However, when I actually visited some third world countries, it was pretty obvious that people who live on a dollar a day don't need computers. They need the basics to stay alive.
"So this idea you've got about getting everyone in the world online... it's kinda stupid and beside the point."
2. Don't screw your business partners.
"Back when Microsoft was growing like gangbusters, we stole product ideas from our partners and folded them into Windows.
"After two decades of litigation and bad publicity nobody trusted us which has made it almost impossible to get companies to build apps for our phones and tablets.
"So if you're tempted to use your market clout to bully the hoi-polloi, remember that someday you might want a reputation for being trustworthy and easy to work with."
3. You'll miss the next wave.
"In the early 90s, I was so focused on Windows that we almost missed the Internet revolution. And I definitely missed the mobile thing.
"Today my erstwhile colleagues are still singing the 'Windows Everywhere' song and, while I wish them well, their tune is sounding pretty tired, even to me.
"So, enjoy riding high while it lasts but prepare for a time when your core product will be old hat rather than hot stuff."