I am fairly sure Gabe expected this, in fact I think he expected more. See, back when Windows95 was first released people were skeptical that Windows would be a good platform for gaming, they cited non-existent technical issues (similar to how they do with Linux now) that drove the employees at Microsoft mad, so one particular employee had the idea to port the most advanced game at the time to Windows, they contacted ID software, and got in an agreement that they would write the Windows port of Doom and give them the code back, ID agreed and after Doom was released for Windows more and more people started to port their stuff over since it was clearly possible. So essentially Windows being a gaming platform was only possible thanks to that employee, who after working with games liked it so much that he quit Microsoft to create his own gaming company which he called Valve. Yup, Gabe Newell is responsible for both Windows and Linux being seen as a gaming platform.