From the original meaning of the initialism, PC (Personal Computer), it would make perfect sense to call a Mac a PC, as it is just that, a personal computer.
However, the vast majority of people distinguish a PC from a Mac - due to clever marketing. This distinction is so embedded in people now, that both PC users, and Mac users do not consider a Mac to be a PC.
So would I be right to start referring to Macs under the blanket term "PC", or would the fact that most people no longer consider the term to refer to Macs make me wrong?