Re: Be afraid!
They haven't given away 300 million. 300 million is the claimed total, but that includes sales of new machines that already have 10 installed, as well as the paid upgrades of enterprise PCs (which were never eligible for the free upgrade).
Upgrades of existing PCs only amounted to a tiny fraction of Microsoft's revenue anyway. Most PCs came with a certain version of Windows, and they'd go their entire life with that version installed. Upgrading to a new Windows used to be one of the things that got people to go buy a new PC, and it was the OEM sales to the PC makers that has long represented the bulk of Windows sales. Giving the product away to the subset of home users that were using 7 or 8 (even if they got them all to upgrade) would not cost MS all that much in lost sales. Most of the free upgrades went (or would have gone, had they managed to persuade all eligible users of 7 and 8 to do it) to people that never would have upgraded if they had to go out and buy 10 and perform the upgrade of their own volition.
That, of course, does not mean MS is just being nice and giving away something because that's how they roll. They didn't give away Internet Explorer out of generosity, and they're not being generous now. One would be wise to be wary of Redmondians bearing gifts.