He failed to recognize that he was primarily exceptional in his preparation for, and early participation in, a brilliant collective of individuals. When he left the collective, his limited individual capacity left him chasing instead of leading.
Guy is trapped inside his own mind and can't get out. Even independent researchers need scientific community to spar with. If you can't explain your thought simply to your peers (followers don't count) maybe you are lost.
Same thing with Erik Weinstein. Left academia early to do something else, became rich. When he finally published the outline of the great thing he had been working for decades, someone easily spotted the errors and that was it.
Einstein's best friend Marcel Grossmann was a mathematician specializing in differential geometry and tensor calculus. Those were exactly the tools he needed for his breakthrough. Grossmann was important facilitator for Einstein. There were others. "Olympia Academy" and his wife for example.
Oliver Sacks experienced Indigo on ahem some substances.