In addition, in a well functioning economy, companies only go public when they want to raise a lot of new money, because they have ambitious plans that can't be achieved with their current sources of funding. Now, really, that's bullshit. Companies mostly go public because the insiders want to cash out. Going public allows them to sell their shares for actual money. But, still, in theory the company should be going public with a story about how they're going to use all the new funds they're raising, otherwise they (in theory) won't be able to con people into investing.

The end result of going public is that the company is no longer in the control of the founders or even the early investors. Now it has a bunch of public investors who don't care about the company culture, don't care about the relationships with the employees or the customers. They just want to see a 15% year-over-year growth in the value of their stocks. That means that pretty often once a company goes public its products or services start to suffer, because you can make more money by squeezing suppliers, finding the cheapest parts, outsourcing jobs, etc.