> 1) That applies to all software. All software -regardless of license- has an effectively-zero duplication cost.That's not true. Copyright allows the copyright holder to enforce a cost of copying in their license fee. You can illegally copy software at zero cost, but that's not the same thing. I can illegally ignore the GPL, too, but I won't.
> 2) You can still sell software distributed under the terms of the GPLv2. You can charge any price you like.
You're being disingenuous. The purchaser can and will inevitably redistribute the software free, plunging its effective value to zero and turning the only tenable long-term monetization strategy into a labor business. Even Red Hat is a labor business in all but name, they live off support contracts and custom development, and I would be incredibly surprised if you could find a business of nontrivial size--say, $2m/year in revenue--whose products are non-SaaS (i.e., not violating the spirit of the GPL while complying with the letter) and GPL-based for which this is not true.
I mean, this is not some shocking revelation I'm saying here--there's a reason the GPL and especially the AGPL are so popular as the crappy side of dual-license schemes, because it allows a company to hamstring those who would derive from their software while not crippling themselves.