Major premise: I (a successful author) sell X number of books each day.
Minor premise: Only less than 5 authors are able to sell X number of books each day.
Conclusion: Everyone besides those 5 authors are not successful because they don't sell X number of books each day.
In a way, you can even consider this as a false dichotomy because it's making you presume that if you don't sell X number of books each day, you are AUTOMATICALLY UNSUCCESSFUL.
There's also the fact that the definition of success is subjective. If we're to agree to certain parameters to define success then those parameters need to be specified so that people would at least know whether they'd like to set the same standards for themselves.
So anyway, now that I got that off my chest, you can search for a certain article about Meredith Wild as a phenomenal indie success and after reading that you can search for a blog post that says only those less than forty authors who were able to duplicate Ms. W's achievements may be considered successful.
Fallacy alert: If you read the blog post, you'll see that an assumption was made about AMZ's statement being true because they're, well, Amazon (appeal to authority). Nothing against AMZ naturally, but it's illogical to assume that everything AMZ says will always be true just because they're Amazon. Then again, this is a moot point since the blog post took AMZ's statement out of context.
Please keep in mind that I'm actually technically better off if I don't talk about this. If I allow other writers to be discouraged then hey, MORE MONEY FOR ME since fewer authors will be writing new books, so more readers may take their chances on my books.
We writers are not in competition with each other. Readers will always read books faster than we can write them so I'm all for keeping readers occupied with other people's work while I slave away on my next book. Let's take turns entertaining readers, yes?
And that's my final say on the topic. <3