I read a HackerNews thread recently where the OP asks about ways to get people working for his startup when he has no ways to pay them. On first thoughts, it's easier to figure out that the OP is a non-technical guy and someone had already posted that when I found the thread. Here are a few reasons why you should pay your startup employees and pay them well.
Shows that you are dedicated to the success of your startup
By spending resources on your hires, you show that you are dedicated to making the startup work, for you and everyone involved with it. A technical startup is nothing without a technical hire. Because it is these people who make it possible, by turning the idea into a product thats someone else would pay for.
Let's look at it from a morale perspective. You, who made up the idea, when you were taking a shower, with such ease, want to hire people to work for you for free. Why should the others, who work for you, pay for their needs from their own pockets, when you sit by a pool drinking lemonade?
What makes you think you own the idea/startup?
When you don't pay people and aren't involved with the project, in writing atleast a line of code, what makes you think that you own the idea/startup? There's always a possibility that the ones you hire might one day get pissed off and... will walk away with the idea after implementing it, claim it to be their own or even worse destroy your reputation in your customers view. Not that's technical hires have bad morale, but when you don't pay them you leave them, you keep the door of evil open.
Anyone can make up ideas. Ideas are dime a dozen (and hell... most are free). Implementation is what makes them valuable.
And if you are trying to hire people to work for your startup for below-avg-pay, it shows that you are selfish and you want to taste success, without even wanting to thank those who led you there.