Top 0.1% Isn't Really Top

It all has to do with comparison. Thing is, percentage is kinda misleading in situations with large numbers. For example, your earnings might be in the top 0.1%, but there are nearly 8.1 billions people, as of writing. That means, you're in the top 8.1 B x 0.1 / 100 = 8.1 million people. Still the top, but millions is still a really large number.

Really, percentages comparison are mostly useful in the local. Ultimately, one should say, compare to yourself rather than compare to others; but if you really have to, let's take a look at some scenarios. Easy to understand -- schools.

Assuming you're top 0.1% in your school, you're seen as one of the most clever person in your school, great! Then, your school aren't that huge, so there aren't lots of people, so you're locally top. But say, if you compare to national or international, your school lies in the bottom 10 percentile, then probably your top 0.1% isn't that top anymore, by-and-large. Of course there are exceptions where your school probably have most of the worlds dumbest people, but they also cater for the worlds most smartest and brightest kids, such that it had the widest separation range of students; but we'll ignore that rare exceptions. By-and-large, or most probable situations, are what we're looking for.

Then, consider the alternative. You're earning the less among your country, you're considered the "poverty" in your country; but your country is one of the richest country in the world, and when compare with the 8.1B people, your poverty is actually top 30 percentile. So, does that put you at the top, or does that put you at the bottom? Separately speaking, you're bottom within your country, but top within the world...

It all comes with point of view and how we see it. A top can become a bottom, and a bottom can become a top, just by changing the point of view. Statistically speaking, this probably doesn't make useful information for an individual; because statistically speaking, you're collecting statistics to get an average point of view, hopefully unbiased and taken into account the whole range of possibilities weighted. But if you're an individual trying to use the statistics to, say, improve your life, or find conclusions that you could target to improve your life, it might (or might not) be misleading.

In conclusion, beware of the mathematics. Ensure you're clear with what "0.1%" is speaking about, nationally or internationally or locally, and what total population of that 100% it's referring to, in order to draw your conclusion accurately whether the study can be useful for you or not. The top 0.1%, just isn't really the top, at least not always.