The genuine polymath is still one in a million

I don't think that's what defines a polymath, for if it does, then none existed. My view of what makes one a polymath is deep --likely cutting-edge-- expertise in several disciplines.

That being said, I agree with the general sentiment that it is increasingly harder to become a polymath these days, especially in the disciplines with lots of active research. To have an expertise in just one discipline it takes years of education (to catch up with progress) and then a considerable recurrent investment of time to stay up-to-date.

If one is to be a polymath in a varied set of disciplines where overlap is minimal (see Leonardo), one would have to go through the mentioned process of acquiring and maintaining expertise for each discipline. This is different for a polymath in a set of closely-related disciplines, because there's only so much more (compared to being expert in one discipline) one needs to do to be a polymath because there's a lot of overlap. But it is debatable whether that even counts as a polymath, a point raised in:

> Is Judith Butler’s supposed eminence in ‘philosophy, linguistics and politics’ enough to qualify her?

This could be seen positively or negatively. One way of spinning it is that he was persistent in exploring ideas. Another way, though, is that something -- mythmaking, hype, his art, whatever it is -- has allowed history to ignore the fact that he seemed to have been wrong more often than he was right, along the lines of a broken clock being right twice a day.

In either case, I think there's something to be said for some kind of cultural and social context playing a strong role in how all of this is interpreted. A different person in the wrong place or wrong time might have been interpreted as a crackpot.

Specialisation came to the fore during the Industrial Revolution and achieved a form of preeminence in the 20th Century that hadn’t existed elsewhere in human history when knowing, at depth, a wide variety of skills and disciplines was either essential for survival or in order to be considered a well-rounded individual.

The internet, not without ongoing battles against vested interests, has solved the discoverability challenge faced with approaching the wealth of knowledge created in the past few centuries. For many of us aspiring polymaths (and I agree with the other comments here that a polymath isn’t someone who knows “everything about everything“, but rather knows “a lot about a lot” or “enough about enough”) the challenge is mental and societal.

We convince ourselves that we must specialize to succeed; most schools and many workplaces promote the same. Yet creativity and insight so often depends on interdisciplinary knowledge and the ability to use our brains to connect novel ideas.

It’s not the right choice for everyone. If you want to be the best in the world (or the top 1%) at something, then specialize. But most of us are more varied than that, which has benefits for us as business owners, or employees, and as humans.