Most things like this have outliers. It doesn't change the fact that being a successful artist mostly relies on having the right social network and sheer luck. The examples you gave had luck that got them to the right social circles - it'd have been easier for either one if they were born into the right sorts of families.

The social circle thing is so prevalent that most artist I've met that sell regularly spend about as much or more time networking as they do making art. Most folks are just stuck having luck enough to sell from time to time, especially if they are outliers and not doing things that match many living rooms.