Because there are very few things to reference, that most people have even a modest comprehension of, that have the scale of $100 or more billion.

Despite the comically predictable replies such posts (GDP vs wealth) always get in threads like this, it's a perfectly valid way to relate size.

The parent didn't say they were the same (in my observation in seeing this same line play out dozens of times over the years, the parent comment almost never says they're the same). The replies are jumping to that assumption as a very low bar way to make themselves look smart.

It's no different than articles that routinely point out the size of a plane's wingspan or the height of a rocket, compared to a building or a football field. The point is to provide the reader with something to stand it next to mentally.

So Bezos can pay to run his country tax-free for, what, 2-5 years?