According to Rick Chapman, the answer is simpler: Microsoft was the only company on the list that never made a fatal, stupid mistake. Whether this was by dint of superior brainpower or just dumb luck, the biggest mistake Microsoft made was the dancing paperclip. And how bad was that, really? We ridiculed them, shut it off, and went back to using Word, Excel, Outlook, and Internet Explorer every minute of every day. But for every other software company that once had market leadership and saw it go down the drain, you can point to one or two giant blunders that steered the boat into an iceberg.
Micropro fiddled around rewriting the printer architecture instead of upgrading their flagship product, WordStar. Lotus wasted a year and a half shoehorning 123 to run on 640kb machines; by the time they were done Excel was shipping and 640kb machines were a dim memory. Digital Research wildly overcharged for CP/M-86 and lost a chance to be the de-facto standard for PC operating systems. VisiCorp sued themselves out of existence. Ashton-Tate never missed an opportunity to piss off dBase developers, poisoning the fragile ecology that is so vital to a platform vendor's success."
Quote: the following quote was added just for the neat statistic.
"In 1993, Microsoft Excel 5.0 took up about $36.00 worth of hard drive space. In 2000, Microsoft Excel 2000 takes up about $1.03 in hard drive space. All adjusted for inflation."