So his net worth is now more than the GDP of my country. Scary.
Did you know, the Stratolaunch has a wingspan wider than the length of a US football field?
The equivalent reply would be: geez, that's a terrible comparison, because the Stratolaunch is not a large plot of ground, they're entirely different things!
GDP is obviously not inherently measured in years. GDP has no set measurement period of time. GDP can be measured in quarters (and frequently is), years, decades, etc. It's most commonly measured in a one year span of time though, and it's likely safe to believe that's exactly what the parent was referring to. One should give people the benefit of the doubt on their intellect and knowledge, imo.
Put another way, yes Jeff Bezos could more than double the GDP of the country in question if he donated his entire net worth as someone else's income. But so could someone with a trivial sum of money (say a single U.S. dollar) by creating a series of dummy transactions with someone else where they constantly exchange the same sum of money back and forth for dummy "services." Yet at some level it seems weird to compare Jeff Bezos with this hypothetical person.
That being said, that's just an intuition. GDP is actually calculated as a dollar amount not a rate. As such I think there's still some worthwhile explanatory value in using GDP as a measure against static monetary amounts in the same way that you can say "this swimming pool has the same amount of water as the amount of water that flows over Niagara Falls in a day" (to the best of my knowledge such a large pool does not exist).
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.
That's like saying it would make sense to compare a plane's wingspan to the speed of a bullet.