When the Windows was launched some 20 plus years ago, it caught like wild fire because it was all of a sudden so easy to use and so convenient to install. The best things that it maintained a constant identity as the product of Windows, while on the other hand Linux went along under many names, such as Knoppix, Mandrake, SuSe, Windows, and so on. With each name (different companies) Linux as an operating system had slight variations. Hence, it was bothersome for people to keep track, and sometime use Linux due to this aspect.
Technically speaking, you will find the GUI is optional in the Linux
operations system while it is part and parcel of the Windows. The separation of the GUI directly affects the reliability and speed not to mention efficiency of a server and hence here Linux scores over the Windows.
Lastly, you have the difference of availability of software. The majority of the software that you find on the market are for Windows and they will not run on Linux unless Windows is somewhere configured as a subsystem which actually goes against the reason of using Linux in the first place.
Hence, till a suitable interface is found where Linux can be compatible with Windows without using Windows itself, have a few clear-cut instructions for first time users and sufficient information on its technicalities, people will prefer Windows to Linux, even if they have to pay to use it.