5000 sales would mean I can confidently commit to writing more works in the future. Anything beyond that is gravy, but that kind of viral take off is difficult to create on command (even for the most successful authors and marketers). But if I can make enough sales to justify continuing to write, then I keep myself in the game with a decent chance of making the big time. One other point I often think about- writers who have a major smash hit with their first work seem to normally sink without a trace afterwards. They most likely didn't understand why they were successful. By contrast those who gradually do better with every production/marketing cycle seem to endure because every stage (including the setbacks) adds to their understanding of the process, the audience and the market.
There was that lady who wrote the story “cat person” that earned her a seven figure advance for a book of short stories. She has done nothing since in that book did very poorly.
 I also wonder if Andy Weir will end up having much of a career. He does have a second book out if I remember correctly, but it doesn’t seem it’s done terribly well. 
I would say about most writers that they don’t acknowledge the amount of work it takes to market themselves their brand and every single book. 
Andy Weir is a great example of the hazards of meteoric early success. His second book is mostly criticized as being a less genuine rerun of his first novel. I suspect his agents advised him to produce something like that to cater to his massive pre-existing audience from the first book. It is analogous to your very first car being a monster truck, leaving you too weak and inexperienced to turn the steering wheel or even reach the pedals easily. By contrast doing something too different as a follow up book risks losing 99% of the readers that loved the first book. Then again, there are worse fates than cashing royalty checks until the end of time from a one hit wonder...
5000 sales would mean I can confidently commit to writing more works in the future. Anything beyond that is gravy, but that kind of viral take off is difficult to create on command (even for the most successful authors and marketers). But if I can make enough sales to justify continuing to write, then I keep myself in the game with a decent chance of making the big time. One other point I often think about- writers who have a major smash hit with their first work seem to normally sink without a trace afterwards. They most likely didn't understand why they were successful. By contrast those who gradually do better with every production/marketing cycle seem to endure because every stage (including the setbacks) adds to their understanding of the process, the audience and the market.
There was that lady who wrote the story “cat person” that earned her a seven figure advance for a book of short stories. She has done nothing since in that book did very poorly.
 I also wonder if Andy Weir will end up having much of a career. He does have a second book out if I remember correctly, but it doesn’t seem it’s done terribly well. 
I would say about most writers that they don’t acknowledge the amount of work it takes to market themselves their brand and every single book. 
You are right on the money about that. 
Andy Weir is a great example of the hazards of meteoric early success. His second book is mostly criticized as being a less genuine rerun of his first novel. I suspect his agents advised him to produce something like that to cater to his massive pre-existing audience from the first book. It is analogous to your very first car being a monster truck, leaving you too weak and inexperienced to turn the steering wheel or even reach the pedals easily. By contrast doing something too different as a follow up book risks losing 99% of the readers that loved the first book. Then again, there are worse fates than cashing royalty checks until the end of time from a one hit wonder...
I think Harper Lee would’ve agreed.