The second of the P's Profitability.

To be fair most niches that exist in the real world also exist online or digitally.Sometimes a target market or demographic are not always conducive to business (If you don't know the difference between thesetwo read here ) For instance the crochet patters for tee pot covers may not be a great niche, but hey it would not be in the real world.

What you need is a hungry market

The late great Gary Halbert was renowned as one of the best salesman of his time i not ever. When teaching a class one day he asked his students what advantage they would want from him, if the two of them were in competition to make the most hamburger sales. The answers were varies

"superior meat"

"better price"
"cheaper price"

etc

Eventually Mr Halbert could stand it no longer and he burst out that his advantage would bet them all, hands down every time.

His answer was a hungry market!

So how do you find out if it is a hungry market.

To have a hungry market it must be an evergreen niche that always has people wanting to solve problems and if Amazon has a book written about it, or the dummies series has a book about it, or is is a magazine on your local new stand then there is already an established market.