I had a friend who had faithfully programmed for Windows 2 for a couple of years. Windows 2 was never popular, so his fine efforts didn't see much use. At that time, the lingua franca of Windows was MS Pascal. However, when Windows 3 came out, MS abandoned Pascal as the primary programming language for Windows and switched to C.
As we now know, Windows 3 turned out to be Microsoft's first big success after DOS. So, my friend found himself sitting on a pile of Windows code that he had written in Pascal over the years that was suddenly useless. Which was ironic, given the newfound success of Windows.
I don't know if that was the first time that loyal MS developers like my friend got Micro-shafted. But it wasn't the last. Even so, switching from Pascal to C turned out to be a very good idea. No pain, no gain, I guess.