They're doing complicated things, but is that headcount in proportion to it? For comparison, Apple's HQ headcount is under 20k, and entire state level governments for small to mid-sized states are in the low tens of thousands of employees. We all know human things generate lots of work to employ lots of people, but the scale still feels a bit off, even if no one can point to exactly why.
It doesn't feel off to me. As others have discussed in considerable detail, operating in a lot of countries worldwide is a lot more complex than it intuitively seems to be, and the complexity scales superlinearly.
I suspect they might be a few percent overstaffed, but I don't think that hurts a company focusing on growth over all else, and I don't think it's even all that uncommon for such companies. It wouldn't surprise me to see a round or two of layoffs once that growth tops out, but it would surprise me if they added up to more than 10% of headcount.