Even inventors inclined to make and sell products themselves have to show potential adequate to attract capital. But, before doing anything else, inventors must make absolutely sure that their inventions work. It represents a person with thick, crepe-soled shoes using a parachute. The parachute is unfortunately attached only to a hat, and the hat is, in turn, strapped under the person's chin. See also the Inventor's Reality Checklist at Arthur D. Little Enterprises.
Answers Estimating profitability is often difficult.
For example, the Department of Commerce has census and other useful data. Also, elementary books on more narrow subjects such as marketing are available. Seeking free help. If none of those are handy, an inventor should directly approach faculty members at local colleges. Sometimes they are looking for student projects.