How large is your addressable market? Is it large enough to interest investors, or is it smaller, meaning you'll have to fund it from revenues?
Does your business idea really meet an unfulfilled market need? You may think so, but do your target customers? What is your sustainable competitive advange that leads you to think you can win over the competition?
If the need is real, how much will customers pay? How do you know they'll pay that much? At that price, can you make enough money to make the business work?