OK, so you have a user who has bought MS office to install on their home machine, and have tried to install it on a Linux system?
The reason why people don't get it is because of the virtual mono-culture that Microsoft have managed to evolve by preventing vendors shipping machines with other OSs.
Let's make the playing field level, shall we. Let's make all the system vendors have to ship and charge for a full retail license for Windows, and take away the lever Microsoft can use to prevent vendors shipping systems with Linux installed.
Salesperson: Hello. I can offer you this machine with Windows at £500, or you can buy the same machine with Linux, for £450.
Customer: Can I browse the Internet, play games and watch media on the Linux machine?
Salesperson: Yes, with some restrictions, although the vendor has paid for all the licences to allow it to do all the normal things, and it's still cheaper.
Customer: And can I write letters and spreadsheets?
Salesperson: Yes, although you will have to use Libre Office, but then again, that is included, rather than costing you an additional £70.
Customer: So I can save over £100 for the same machine! Where do I sign?
Of course, it won't be quite like this, but if Microsoft had been prevented from blocking Linux 10 years ago, we would have been in a different place now.
And don't quote Netbooks at me as a Linux failure. The versions of Linux that was shipped, and Microsoft effectively giving XP away after it was withdrawn from support poisoned that market.