OpenBSD was a great OS back in the late 90s and even early 2000s. In some cases it was competing neck to neck with Linux. Since then, well, Linux grew a lot and OpenBSD not so much. There are multiple causes for this, I will go only through a few: Linux has more support from the big companies; the huge difference in userbase numbers; Linux is more welcoming to new users. And the difference is only growing.