You can't be a polymath by choice. Its merely a label other people apply. Start with the big set of everyone. Then select the subset of people with hobbies (

You can't be a polymath by choice. Its merely a label other people apply. Start with the big set of everyone. Then select the subset of people with hobbies (terminally boring people live to work... perhaps exclude the seriously ill) Some fraction of those are interesting (watching TV doesn't count, boring). Some fraction of those interesting hobbies are something they're good at (my flute playing makes dogs howl in pain, frankly I don't care I'm having fun even if no one listening is having fun). Some fraction of those hobbies that are interesting where they have skill have some public component, like the article examples of writing books and holding lecture series. Edited to add another level, people that have very public interesting hobbies that are highly talented, they might get public attention, which is rarer than you'd think. Then, that tiny little subset, some of them, get labeled as polymaths.