My comment isn’t really a viable argument but I’ve been thinking about how an advert for Linux would be:

“The top 500 supercomputers in the world run Linux, don’t you want to feel like having a supercomputer at home? Why wait? Get your Linux for free today!”

Not really to be taken seriously, but if you want a real argument and example:

My laptop is really laggy with windows 10, and it came preinstalled with it. Recently I tried dual-booting Linux and Windows, and Windows was simply too slow. I am so accustomed with Linux’s speed that I wiped Windows off it. Never again.