The government granted monopoly (copyright) is what gives open source licenses, like the GPL, their power. Depending on the exact license, you aren't allowed to make a copy of non-proprietary software either. Copyright doesn't say you aren't allowed to make a copy, it says that the owner of the copyright is allowed exclusive exploitation of the work, which is sellable/transferable to other parties, and is often restricted based on conditions -- with proprietary software, these conditions are usually only money changing hands.

The GNU license requires all forks to also be open source. This means that I won't be able to add open source software to my proprietary application without all of my changes also being given out for free.

The Free Software Foundation also sues companies in court for not complying with their license. This doesn't really sound like anything different than the current copyright system.

I would not want to live in a world where I am forced by law to give out the source to my software.