Creating software isn't cheap, or effortless, however once it is completed it can be duplicated and shared at near no additional costs.
So using good old Economics 101 supply and demand you have a fixed demand, and an infinite supply, so the market rate for any software is near $0.00 below the cost to make it. Software does want to be free.
I don't know why more open source projects don't just charge for their software. Sure this removes Freedom 0 (the freedom to run), so it's not (big-O) Open Source. But it preserves all the important tinkering freedoms, especially if original authors get a cut from sale of derived works.
What you wrote above implies that most users will pirate anything not completely locked down. I don't think that's true, especially for business users, and especially if a purchase comes with support. Charging is better than a donation model, where donors are made to fee like chumps, usually gaining nothing more than karma, and freeloaders haven't done anything wrong.
The old RMS model of making money off of software is selling the distribution. Putting it on Tape, Disk, CD... Some physical media, then you can add manuals to jack up the price. These physical media reduces the available supply so you can make money off of software. Now with nearly everyone with high-enough speed internet access, such physical distribution of software is antiquated. And not a good business model.
Quite true. You can't make money from Open Source software in itself. But you can from software that's free in every way except price.