I know three. And know OF many more. Harold Robbins, Mickey Spillane are just a couple of guys who decided there was money in writing and just sat down and kicked out the best-selling work of their times.
As far as I'm aware, Mickey Spillane spent about seven years writing for Superman, Batman, and Captain America comics, before he even decided to start work on
"I, the Jury" ...
(Not to be pedantic, or anything ...)
Anyway, as John said, it's obviously
possible for that kind of thing to happen. On the other hand, it's always
possible that I might win the lottery at some point this week. INCREDIBLY unlikely ... but
possible.
It's NOT brain-surgery actually. So much of writing is just somebody's way of speaking, of what's going on in their head.
If you
do find it that easy to write a novel, and get it published, then I can only take my hat off to you! Well done! But if you
do have a collection of rejection letters, like
most writers, then surely that's proof that it's
not that easy ...
And besides, isn't brain surgery
also about what's going on in somebody's head?