It's my conclusion based on what's selling on Clickbank.
I'm in the latter market, selling a $47 ebook helping women deal with a narcissist. Initial test years ago gave 2% CVR from Adwords. Broke even in one month.
But today, even though FB lead ads get me leads 8c/lead, sales are rare.
Should I try to differentiate from the competition (lots of free content today) and develop backend to improve the average order value or change the niche/market?