I'm not sure what you mean here. Do you mean to say that 90% of writers/people never sell a story? And the ratio of stories written to stories sold is 50:1?
.
No, I mean that the average selling writer had to write fifty short stories before writing one that was good enough, and that fit the markets well enough.
For most, learning how to write well enough to sell in an
extremely tough area takes time. Learning how to give editors the kind of stories they really want can take even more time.
Now and then, a writer does sell a first short story, or a second or a third, but the simply fact is that every now and then someone comes along who learns how to do anything extremely fast.
The short story market is the second toughest on earth to crack, if you mean paying markets. Only magazine poetry is tougher. Paying markets receive a lot of submissions, and most of them constantly receive stories from the best writers on earth. Space is limited, so in order to publish a story by a new writer, an editor has to reject a story by a well-known writer. Probably a dozen or more stories by well-known writers.
This means your story must, in some way, be better than all the stories the editor sees not only from hundreds of other new writers, but also better than the stories the editor receives from well-known writers during that submission period. Not as good as, but
better.
This is the difference between short story and novel publishing. When you write a horror novel, the publisher does not have to reject Stephen King in order to buy and publish your novel. With short stories, however, an editor can buy and publish only a few short stories per issues, Rarely fore than five, and often only one or two, depending on the mag. In his submitted stories stack there may well be a story by Stephen King, and often as many as three dozen othe rstories by writers with names and reader would recognize.
There will probably be another bunch of stories by writers who aren't famous, but who do have some good credits.
Even if the editor could buy ten stories, he's still going to have to reject some proven, well-known writers in order to buy yours.
This doesn't even count the hundreds of other new writers who also submitted stories during that submission period.
Fortunately, this is possible, of course, but rarely on a first, or second, or even a twentieth story. It happens only after a writer gains the skill to match his talent, and when he learns to not only write well, but to write stories that fit the markets. This is not always the same thing.
And, realistically, there are
millions of short story writers out there. Numbers alone mean that only a very small percentage will ever sell a short story to a paying market, let alone to a large, credit worthy market. And only the top one or two or three percent, maximum, can do so reliably and at all often.
A lot of writers think selling a short story is easier than selling a novel. For a tiny few, it is, simply because some people write short stories well, but do not write novels well. For the great majority of writers, however, it's a heck of a lot "easier" to sell a novel to a mainstream publisher than it is to sell a short story to a credit worthy magazine.
The only reason good short story credits matter is because they're so incredibly difficult for most writers to get.