Volkswagen was greedy. They wanted to be the diesel kings in America, but meeting emissions regulations while offering good performance and fuel economy was too expensive. Cheating seemed cheaper at the company where engineers couldn't say "no" to their bosses.
The customers were greedy too, though you can't really blame them. They wanted all the torque and fuel economy of a diesel, without diesel's excess emissions. Unfortunately, diesels are dirty by design and need a lot of expensive hardware to keep their toxic particles under control. And even then, that cleanness won't last forever under everyday conditions.
Either way, American customers got cheated by a German brand, and now, some of their executives have to face trial on conspiracy charges while the cars get stripped and crushed despite being trusty daily drivers with more to offer. That's how it goes.
With all those old diesel trucks, ships, locomotives and tractors out there keeping the world in motion while spewing black smoke into the air, it seems like Golf TDIs are the real victims here.