The competitors mistakes
Seriously, the playstation was originally the "Nintendo Playstation" then they parted ways(for various reasons) while sony had basically the perfect console which led to Sony dominated the next 2 generations.
Microsoft bought Rare, and Nintendo did nothing to to try and keep them(which lead to Nintendo not being able to produce enough games the last 2 generations). The only reason why the 360 caught on was because the ps3 was near impossible to code for and therefor had a bunch of terrible ports. That plus Sony creating a $600 console.
The 360 and ps3 didn't really start booming until Nintendo made the mistake of abandoning the wii.
I'm sure I could think of plenty more, but the bottom line, is that had those companies NOT made those mistakes, the sony playstation would have never existed, and Nintendo may have become the sole home console maker, just like they basically own the handheld market. The psp was the only handheld to actually make a decent amount of profit, and unless the vita somehow manages to pull through, psp may have been an isolated incident.
Something...Something...Games...Something
