While there are free alternatives for a lot of software available on Linux, the simple fact is that there is a lot thatt is Windows, or Windows/Mac, only.
Games are a great example. While you could screw around with WINE and get World of Warcraft running, it's never going to run as well as it would in its intended environment, and there's every possibility thatt an update to the game that works fine on Windows will not work on Linux with WINE.
There are, however, many use cases for Linux where it can work quite well. For instance, if you're using Chrome to browse the web, Thunderbird to check email, LibreOffice to edit documents, you might do great on Linux. Just be sure it works with all your hardware (printers especially) before making the switch.
I have a laptop which runs Linux (Ubuntu Mate to be precise), and it's great as far as it goes. Getting my printer working with it (an older Canon multi function) was much more annoying than on Windows, particularly when I decided to use it with my Windows box and share it from there. It was doable, but very annoying figuring itt out. I still couldn't use it full time, however. I enjoy playing games on my computer, and not many of them come with Linux support.