With 2%, you would roughly find someone using linux for every 50 computers you stumble upon. Maybe it’s not as far off as you imagine. However, like someone already mentioned, the distribution isn’t homogenous, and maybe there are concentrations of linux computers in some universities, businesses, etc.
Or maybe linux users don’t go out as often as the average person, so you never get the chance to see them in coffee shops lol. If the other linux users are like me, that’s exactly the case…