I honestly feel unethical promising things before I can deliver them. But I've discovered that people with a business background are less squeamish about that.

Oh, and I partly agree with your first point, you are always asking people to invest in a combination of you and your product. Just what combination depends on the stage of development you are at. Even a buyer of a mature product places some faith in the ability of the supplier to support the sale.

In my engineering career, the most successful products, without exception, have been the ones where customers have parted with at least some cash in advance of substantial development. I didn't understand this in my early career, and it always frustrated me to under the gun to develop things that have already been sold. Usually, the first customers were sold on a mix of mock-ups and PowerPoint presentations. Experience taught me the sales guys were right.
Evert single complete flop I have seen (there have been plenty) involved a build-it-and-they-will-come product.
A successful product or service needs customer feedback during it's development and the only feedback that counts involves prospective buyers choosing whether or not to part with cash.

The majority of my point still stands, though.

1. no prototype -- people are investing in you, not your product (although with some sleight of hand you may have convinced them otherwise)
2. prototype -- you still built something, you just decided when to stop.

The whole of this article still doesn't show the crux of the issue: build first mentality is a slippery slope, because it doesn't say at what point anyone has stopped 'building' to start 'selling'.

See, I disagree with this -

> I don’t think I’d even want a buyer to throw money at me without me proving that I can do something for them, which would mean at a minimum to prove that I can build, or that I am almost there anyway.

I think you've got a build-first mentality, and it's less likely to lead to successful business.

If you're not sure what you're doing is possible, say that. Say, "I'm not sure if this is possible, but if it is, here's what it'll do for you" - and ask relevant people to back you. If your idea is solid enough, they might not say yes, but they'll at least be flattered you ask them and you'll get friends and maybe good feedback.

You kind of don't want to be seen with something half-baked, but the end result is that you're more likely to spend months or years on something that turns out... half-baked. Better to own it early. Be entirely honest and scrupulous - let people know your risk factors, what you're unsure of, etc. "Sell first then build" doesn't mean "Don't do anything until you make a sale" - of course not. Rather, it reflects your priorities - do you prioritize relationships with customers, marketing channels, and an understanding of market needs more or less highly than the inventing itself?

Inventing as a hobby can be pure inventing, but if you're trying to build a business - then, being in touch with customers, building relationships, and understanding marketing/distribution channels will make you far, far more likely to succeed. And quicker, too.

If you're nervous making a promise, ask yourself what specifically you're unsure of being able to make, then prototype only that. Then start selling, and when you have customers you can fill out the 99% of the product that's routine construction.

My guess is unless you're on the bleeding edge of physics or biology where money can't buy a product, you can make anything you sell -- the bigger it is and the sooner it's needed, the more you'll be receiving from the buyer to fund development.

I don't see how this is a helpful tip. In both cases you cite, you're still building something. In a tech startup, you'd probably call it a Minimum Viable Product. You can call it a 'prototype' or whatever, but you still have something that you can show to interested buyers. I don't think I'd even want a buyer to throw money at me without me proving that I can do something for them, which would mean at a minimum to prove that I can build, or that I am almost there anyway. Would you want to give money to someone based on nothing but promises and dreams?

It's more interesting and infinitely more valuable to know:

1. when to stop building that MVP
2. how to sell it

And I'd rather read about either of those.