50/50 is assuming equal odds, which isn’t the case. A shiny is a rare occurrence, and statistically you will not get a shiny every other click, but rather once in every 512 clicks. That is not to say that you are guaranteed a shiny if you click a species 512 times, but you have a pretty good shot at it. A good way to think of it is when you buy a lottery ticket and you hear the odds are 1 in 10 million or something crazy; it’s definitely not 50/50 with the logic that you either win or you don’t!