What authors would have been even better but succumbed to financial considerations?

It's kind of conventional wisdom that Fitzgerald altered his stories to get them into the big magazines of the time. And then of course the tried his hand in Hollywood.

And Dickens had to structure his novel for serial publications in newspapers/magazines, which was the in thing back then.

Sometimes I think the later work and selection of what to work on from GRRM may be rooted in his recollection of his younger days and kind of struggling to make ends meet as a writer. (I could be off on that but that's how it strikes me sometimes).

I've never read much of Stephen King beyond The Stand but I think he churns out the books at a pretty good rate. Not sure how it's affected his stuff though.

Of course, I guess the opposite also applies. Some writers like John Kennedy Toole would have likely benefited from putting out more stuff, even if a lot of it was lesser quality. But I think his problems dealt more with mental illness.