Taleb made a lot of money trading, his firm failed but running a successful business is not trivial and his ideas ended up working when he took up an advisory role rather than an executive role. Unlike other financial "influencers", he actually seems to understand mathematics to a high degree.
He made money when he was working for other people. He did not make money when he tried to trade off his ideas. That was 25 years ago, since then he just broadcasts his ideas.
You don't have to be self-employed to have skin in the game, that's ridiculous.
How many op ed writers have tried to have skin in the game at all? How many of them produce writing which is actually high quality and not just concern trolling about China or what have you?
I like to say, traders and people you put money on the line are often far more honest about economic policy, than economic influencers like The Economist.
The quote originated with George Bernard Shaw back in 1903, not Nassim Taleb. And it has always been a lazy take. Some people just prefer to write (or teach).