The only way to know if your idea, project, venture, or service will work is to try it. Plain and simple.
Sure, you can ask prospective clients what they need, want, or would pay for.
You can collect data and stats to make an “informed” decision. You can even pre-sell your idea and see if it sticks.
But the only way you really know if your idea will work is to try it. To put it out there and see what sticks.
That doesn’t mean you should neglect research. It’s critical to succeeding in cases where you’re targeting a brand new market, for example.
But if you’re looking for guarantees, there are none. Gather your research, do a gut check, then see if it builds traction.
There are no guarantees in business.