Can you name any real-world examples of this happening?

Actually, I can. I know before Minetest (a FOSS Minecraft clone (they’d bristle at being called that, but anyway) that has since renamed itself to “Luanti” - I reccommend it, actually) officially supported Android, somebody ported it to Android (I don’t remember what they called the clone) and put it on the play store for money. Now, Minetest wasn’t under a copyleft license, so the clone wasn’t even FOSS (nor was it legally required to be.) I don’t remember any malware being involved. The Minetest community did all heave a collective groan when a wave of clueless people who didn’t realize it was FOSS started joining Minetest servers. People in the Minetest community definitely resented the clone. But beyond that, no real harm came to the game or its players. Some folks paid for an Android Minetest client that didn’t afford them the freedoms guaranteed by the Free Software Definition or Open Source Definition, but at the time the official Minetest client didn’t support Android. Aside from that, I don’t know of any harm that came from any of that. And had Minetest been under a copyleft license, even less harm would have come of that.

Also, in practice, anyone who’s only out to get a quick buck is going to either avoid copylefted code like the plague or just blatantly violate the terms of the license. They’re unlikely to actually put forth the effort to compose a proper GPL compliance plan. (In fact, the ongoing U.S. court case “SFC v. Visio” is very apropos. Visio is named as a defendnt in that suit specifically for blatantly violating the terms of the GPL. Specifically the copyleft portions.)

And if someone who does just want to make a quick buck clones some GPLd code and sells it in compliance with the license, I’m still not convinced that does anyone any harm. The GPL was also designed with non-programmer empowerment in mind, specifically allowing the use case where if a non-coder wants a feature added to a piece of GPL’d code, they can commission a coder to add it. But I’m not sure the Grayjay license would allow that even if it would allow one to make changes themselves noncommercially.

I dunno. You seem to be really hung up on “contrubuting nothing”. And mind you, I don’t think that’s uncommon. That’s a big part of the whole “post-open-source” thing Parens is involved with these days. If FOSS as a whole was floundering right now in a way that money could solve, I maybe could get on board with the idea that there might be improvements that could be made to the existing FOSS paradigm. (Though something like legally-preserved nag screens in source-available software seems at best a clueless and ham-handed approach to that problem.)

Much more concerning to me is that software respect users’ rights. I mostly won’t use software I don’t feel I can trust (either legally or security-wise.) And FOSS is software I can virtually always trust. When I’m publishing software, I do so under the AGPL v3 because I kinda don’t care if anyone sells it. (Though they can always get a free version from my GitLab (yeah, I switched to GitLab before Codeberg was a thing).) I do care if someone distributes (for money or gratis) my code in a way that doesn’t afford the end user the four freedoms. Which is why I use AGPL v3 over other options like non-copyleft FOSS licenses or noncommercial licenses.

And, just to repeat this, again, I’m not angry at FUTO for releasing their code under non-FOSS licenses. That’s enough to make me not want to use their software. But not enough to make me resent them the way I do. The anger is at the way they’ve been sabotaging Open Source to the best of their ability while misrepresenting themselves as consumer rights advocates.