Because his "billions" were on paper, in the form of Akamai stock (and "billionaire" seems like a stretch; I don't think Akamai was worth enough for him to have

Because his "billions" were on paper, in the form of Akamai stock (and "billionaire" seems like a stretch; I don't think Akamai was worth enough for him to have been a billionaire, even on paper, at the time he died). He was the CEO of Akamai, and on a business trip at the time. This was right during the dot-com bust; Akamai was losing customers left and right, and cash was very short. You don't make a good CEO by chartering private jets for your trips while your company is busy laying off employees because business has just dropped.