Quite often, I hear this argument that is supposed to be very convincing: "But our enterprise has millions of dollars invested in infrastructure X, it is our duty to protect it".
Give me a break.
Let me give you an example: In 1997, I've invested $2000 into a highly modern computer. It had the brand new Pentium MMX 233MHz CPU, whopping 32MB RAM, and incredibly large 2GB hard drive. It even had the SoundBlaster. Forget the fact that 12 years and countless generations of computers passed by since, I still must protect my investment and support and nurture the obsolete monstrosity with less computing power than a phone in my pocket?
What part of the message you still don't understand?