Once you grasp the concept, you can apply it quite easily in your daily life. Going to parties and any kind of social event gives you convexity - nothing really bad is going to happen to you, but you might end up meeting the love of your life or meet a potential business associate who transforms your career, etc. You don't really lose anything except an evening's time, but there are all kinds of potential lucky benefits.
He also uses the concept, naturally enough, to discuss financial investments - if you keep 90% of your portfolio in cash or gilts and then put the remaining 10% on hugely risky investments the worst thing that will happen to you is you'll lose 10%, but there is no upper limit to your potential gains.
What interests me most are his ideas about convexity and creativity. He cites the example of Einstein as somebody who had a convex career. He was a patent clerk - the most boring, dependable, steady job you could imagine. It gave him sufficient financial security with very little risk. But then in his spare time he wrote insanely ambitious academic physics papers and sent them to leading journals. He was very secure against bad luck (steady job with very little chance of losing it) but had the potential to benefit massively from good luck (if his papers got published).
This may be the ideal: no real exposure to bad luck; huge exposure to good luck.
A lot of successful writers are like that. Stephen King had a safe and steady job as a teacher but in his spare time wrote stories; one day Carrie got bought for $200,000. Tolkien was a jobbing academic (as much as that can be true of an Oxford don) while he wrote what at the time were pretty unusual fantasy stories which suddenly one day became very successful. It's certainly not a pattern that the Truly Great Creatives follow (e.g. Van Gogh) but it's interesting how many creative people entirely unconsciously have a "convex" way of doing things.
Is there a lesson in that for people who write gaming materials? It's not as though you're going to ever be Stephen King. I think the way to be convex is basically to be as ambitious as you can possibly be - no half measures. If you are going to spend time writing something you ought to go hugely risky with it. Think of yourself like Nassim Taleb's investment portfolio. 90% of your time is more likely than not an ordinary job. That's safe. So in the 10% of your time you have for creative pursuits, don't play it safe. You want huge exposure to good luck - the potential that what you create will be absolutely bloody brilliant. If it's not you'll have lost almost nothing, and if it is you'll be much happier than if you just did something that was just goodish and solid.