[flaubere]

Although von Neumann was certainly a genius who happened to be in the right place at the right time, he's also an example of how groups of people can create a culture seemingly much more important than the effect of one outstanding individual. Lipót Fejér led a school of analysis at Eötvös Loránd University in Budapest. He ran a seminar, was the centre of a large group of young mathematicians who worked together and was enormously influential.

Hungary has a disproportionate number of the world class mathematicians of the 20th century. The numbers are even more extreme when you consider that those mathematicians are all from Budapest, all from Eötvös, and the vast majority of them Fejér's supervisees. It's totally plausible that Fejér created an environment where people who might otherwise have been middling mathematicians, decent engineers, or never have found their niche, were transformed, by collaboration and inspiration, into the likes of von Neumann, Erdős, Pólya.

Even today the Eötvös school of analysis and combinatorics is a significant powerhouse, with most members direct mathematical descendants from Fejér. And there are other branches such as Cambridge combinatorialists where the influence of Fejér's students and grand-students has been key in the formation of world class mathematicians.