This guy raised $650 million from investors (or close to it) in less than 4 days? And the people buying this debt KNEW he was going to buy bitcoin with it.
the key word here is convertibles. So let's say BTC tanks and MS shares also tank and then when the debt comes due and MS can't pay what happens is basically that the debt gets converted into stocks. But since the stock has most likely crashed that means that the bondholders get s very large share of the company. So if they feel that MS has other assets that they value this is a win win, because either they get their money back in four years or they get to buy lots of shares super cheap.