Your normal family budget and government economics works the same way. If Dad wants to buy a monster truck, Mom & the kids have to go without new clothes. Or if the kid gets accepted to a private university, the entire family has to do without to pay for tuition. Or if Mom wants a new dress, Dad can't get the latest electronic gadget. If they try to buy it all, they go bankrupt. And government programs work the same way: they ultimately bankrupt the nation, because all they can do is raise taxes to fund the new programs. The only way the government can get money is to take it from YOU, who earn it.
Free markets, on the other hand, actually do something a little magic. They create wealth. Now this is a difficult thing for many people to visualize, because all they know is slices of pie. When faced with too many people shouting for pie, all most people can think about is how to divide the pie into smaller slices.
The free market, on the other hand, finds a way to make more pies so everyone who wants one can have a piece. And this is the magic of wealth creation. Clever people, with the incentive of doing a little better for themselves and their families, find a way to make more pie. And if the pie is tasty, these clever people become rich! It's as simple as that.
Simple, but not easy. If it were easy, everyone would do it.
What is the trick to creating the magic? Eliminate obstacles, focus only on what is important, and work very, very hard. For a great treatment of how startups work, see How to Make Wealth by Paul Graham.