Plus downloading a virtual machine to run it in, since we were talking about paid software and Linux users. I'm typing this on a MacBook. I've used OS X for home (no chance at work - too limited software and hardware) for 12 years now and have NEVER used it to edit a picture or video for home use. Only ever needed to do that a few times for publishing at work, so Gimp worked fine. Back to my point, Linux users aren't necessarily adverse to buying software just because the OS is free. I doubt they really notice that they have to pay for Windows, at least with a store bought computer.
Using Photoshop over Gimp every 4-5 years is not worth one single additional second to me. YMMV. Never used it. Never plan to. Gimp is already installed on the system - on the Linux system. I've definitely never needed it at home on a Mac where there is, in fact, a native version.