Just knowing a bunch of stuff doesn't seem to fit the meaning of the phrase to me. To qualify as I see it, one would need to not just be familiar with various sciences, but also make real contributions to more than one relatively unrelated field (or have real success as measured in some other way for non-scientific fields, such as Leonardo's paintings).

And I don't think anybody in the last hundred years qualifies, because the way science is done now just doesn't allow it. To have real influence in any field, you need to do research. To do that, you need money and equipment and time not spent working to make a living by some other means. To get those, you need to be an established figure in the field already, with an advanced degree and some kind of employment or other such contract with an established university, government agency, or company (a company which does its own research for commercial purposes). To get any of that, you need to invest a bunch of years of your life in the dedicated pursuit of one field. Even if you're rich enough to be able to fund yourself without working for an income, you still need years of formal education and establishment of your own credibility in the relevant community of scientists in order for whatever results you get to be taken seriously, which ultimately makes your fortune merely a convenience in going through the standard process rather than a way to bypass it.