I don't think the need-to-have versus want-to-have distinction is sufficient to kill a product. If you niche the product down to a very narrow market you might

I don't think the need-to-have versus want-to-have distinction is sufficient to kill a product. If you niche the product down to a very narrow market you might find people who need to change their habits. It could be a matter of life and death for them. For example, someone trying to lose weight, or break an addiction, or study for an exam that has life-changing outcomes for them.