[ghazak]

You may be able to make a sale and then build it and still keep the sale, but if you think that this is too risky with respect to reputation or having a customer depend on what you’re selling be ready, it’s still worth going through the sales cycle until you’ve found something you can sell.

It won’t magically get easy to sell the product when it’s ready, so it’s possible eliminate bad ideas which are hard for you to sell early, even if you let the sale fall through towards the end.