With the emergence of more and more people wanting to be entrepreneurs, there are naturally more people pitching their ideas. There's nothing wrong with that when those pitches come with a prototype or something one can look at, but often they're accompanied by nothing but words. When I moved to New York and got into the startup scene in 2006, everything was a demo. Now everything is verbal and that can be a real problem when it comes to developing a workable idea.
Talking Builds Up Your Idea in Your Head
If a lot of what you're doing early on is spending time talking about your idea to others, you're going to end up convincing yourself that your idea is the next big thing. You will have built your own groupthink because the people you talk to will rarely (if ever) give you honest feedback. They'll just smile at you and nod. They'll tell you how good your idea is and that they can't wait to use it and know plenty of folks that would want to use it too. Nobody wants to be the mean guy taking the wind out of a new entrepreneur's sails.
What comes of this is that after you've gone out and told a few dozen people about your idea, you'll come away with a "can't lose" attitude. Then when you finally get around to building it, you won't objectively critique what's good and what's bad about it. You'll think everything is bound to work and you won't look at it closely enough. This can lead to a badly flawed product that has failed to anticipate rational objections.
Little is Learned From Talking
I strongly believe that early on — say between the inception of an idea and an initial prototype — nothing should get between you and the idea. Any influence from outside is a distraction and can be counterproductive. It's similar to doing A/B testing when your product doesn't have enough users to warrant it. There's just not enough data.
That doesn't mean that you shouldn't talk about process with people who are more experienced than you, but whatever a light bulb has lit up, you need to remain as uninfluenced as possible early on. The best thinking about your product will come from actually building it.
You’ll Get Better Feedback with a Prototype
You'll get a lot more useful advice from others when they can sit down with you for thirty minutes and discuss the prototype you've built than when they're just hearing about the idea. That's why most investors prefer a working demo to a slide deck. They want something they can play around with. Something tangible. They want to get a complete picture and nothing short of a demo provides this.
The other advantage to showing someone a prototype for the first time is that for you might have just gained yourself a new user! They couldn't have been a user if you were only talking about it. But now if they like what you've built, you've just added one more person to your user count. They can even tell a friend! Now you've got two users. Amassing passionate users early on is nothing to scoff at.
Talking Delays Building
This is the most obvious point, but it's true nonetheless. Every minute spent having coffee or lunch pitching your idea to someone adds up to hours taken away from building your idea. Not only are the hours away from your computer lost, but also there's the time spent getting back into the zone when you're back at the computer. Careful development requires painstaking thought, so time away from your desk shouldn't be taken lightly.
A side note to that: Some of my best thinking happens away from my computer and desk, so not all building needs to take place there. It's very effective to vary your surroundings early on (coffee shops, friends' apartments, friends' offices, etc.), because changing your mood and your environment can trigger new thoughts.
It’s Not About People Stealing Your Idea
Too often the only reason new entrepreneurs won't share their idea early on is that they're worried that people will steal it. Get it straight: nobody is going to steal your idea. I don't think I've ever heard a case of someone's idea being stolen pre-prototype. We're actually so bad at explaining ourselves at this stage — "you know it's like X hot startup + Y hot startup," we say — that it's never clear what there is to steal anyway.
Now That You’ve Built a Prototype...
Talk it up! But, still do that selectively. You want to confine the circle of your initial users (friends and family) so that you can squash any bugs and make tweaks while getting initial feedback. You only have so many chances — usually only one — to grab peoples' attention and if you go out and make a lot of noise too early, you may lose those people six months from now when you actually have something good built.
Furthermore, now that you've got a prototype built, your thirty-minute meetings with people will be exponentially more effective than just chatting with them. You can get real feedback on a real product — none of this "I think I'd use that" bs. You'll have a much better idea of what they think, and most importantly, you'll understand why they think that way.