1. Bitpay does not mean, that ALL the bitcoin get converted into fiat instantly.
2. Putting some millions into Bitcoin is nothing for Microsoft: NOTHING. Like every big company they had R&D-projects, over years, that failed in the end and burned some Millions.
3. Just because, they are just accepting Bitcoin from the US and for a small group of products, doesn't mean it will stay that way FOREVER.
yet overstock hoards coins..........
need i say more?
If Microsoft decides to begin hoarding Bitcoin, I will post a picture of myself here, in the buff, with your username painted across my chest.