Poor phrasing on my part.
When I said "Microsoft does not need to sell to business...", I meant the word 'sell' to mean 'advertise'. I didn't mean MS doesn't need the income from the business market. I meant MS doesn't need to advertise W8 to business because it's already established there.
Businesses may not be upgrading at the rate MS would like, but the majority of existing Windows users replacing with a new Windows product. Few jump ship to Apple or Linux.