How do you feel about solo entrepreneur products that are solely for individuals? e.g. Pinboard, Tarsnap Idea being purposefully stay small - keep costs down,

How do you feel about solo entrepreneur products that are solely for individuals? e.g. Pinboard, Tarsnap Idea being purposefully stay small - keep costs down, so you don't need as many customers to succeed. My gut feeling is there is a sweet spot (likely below $20/year) where it's more of an "impulse buy" rather than a purchase that needs consideration.