You don't know much about the GPL, do you? You were almost right about one thing: "nobody can take the code private." Only the copyright holder has the right to change the license. Anyone else, however, can make changes to the software, not provide those changes back to the copyright holder AND make money by selling GPL software. Any modifications you make to the software are also licensed under the GPL and you are not required to share the source code with anyone except the people that use your modifications. If you sell object code (binaries) of the software to customers, you are required to provide the source code to your customers upon request. The price you charge for the software is only limited by what your customers are willing to pay and you can't charge anything more for the source code.
It's not difficult. Reading the GNU project's philosophy on selling GPL software might help you better understand how it works. Looking up "selling GPL software" on Google is also an option.
Old programmers never die, they just become managers.