Early on, before a leader in the PC market was established, investors had the choice of betting which horse would win--Bill Gates at Microsoft or Steve Jobs at Apple.
Many people did get rich betting on Gates, so indirectly, yes, Bill Gates does show that people have gotten rich betting against Jobs. The hyperbole is nice, but only that--hyperbole.
"The first Macintosh was introduced on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a graphical user interface rather than a command-line interface. The company continued to have success through the second half of the 1980s, only to see it dissipate in the 1990s as the personal computer market shifted towards IBM PC compatible machines running MS-DOS and Microsoft Windows."
Check your timeline. By 1990 betting on Microsoft was not betting against Steve Jobs.
Steve Jobs left Apple in 1985. Windows 1.0 was released in the same year. However Windows struggled at that point. According to Microsoft (see http://www.microsoft.com/windows/winhistorydesktop.mspx for confirmation) the first successful version of Windows was Windows 3.0. That was released in 1990, and its main competitor was a severely mismanaged Apple. At that point Bill Gates was emphatically not competing against Steve Jobs.
When you're investing in Microsoft and not in Apple, that's a bet against Apple. And it wasn't just investors that had to make that bet ... software developers and customers had to pick.
In the early '90 support for Apple's hardware / OS was a second class citizen and it still is in many areas.
Many people did get rich betting on Gates, so indirectly, yes, Bill Gates does show that people have gotten rich betting against Jobs. The hyperbole is nice, but only that--hyperbole.