Let me start off with I do not condone piracy in general, but I can think of 2 reasons why it would be OK to pirate a game or OS.
If the game or OS is no longer available, example Windows XP it is unavailable and yes there is Linux and yes you can use WINE for most things, but some older games need Windows XP (or even older) to function properly.
The game is available but at nostalgia prices, example Mechwarrior 4 compilation for 125$ that's more then I paid for it new. MWO has no madcat 🙁
If the game or OS is no longer available, example Windows XP it is unavailable and yes there is Linux and yes you can use WINE for most things, but some older games need Windows XP (or even older) to function properly.
The game is available but at nostalgia prices, example Mechwarrior 4 compilation for 125$ that's more then I paid for it new. MWO has no madcat 🙁