To be clear anyone with a few million in savings can take on multiple citizenships as a hobby, maybe OP just considers it table stakes for billionaires, as in, why wouldn't you.
St kitts and Nevis is only a quarter mil, tho I don't know what benefit that would confer unless you're coming from a country without visa free travel
And for what it's worth, UAE citizenship is not for sale directly, you have to actually live there long term
Residency is pretty much for sale in the UAE. However it is virtually impossible to be naturalized in the UAE through the official route. Most of the country is foreign born and there are lots of benefits to being a citizen so this deliberate. It requires something like 30 years of uninterrupted residency. Most people who get it are basically granted citizenship by a king. That’s why when you look at the list of Emiratis on Wikipedia the ones who aren’t Arab are almost entirely elite athletes and businessmen with political connections. It’s interesting that France and the UAE granted him citizenship and hacked his phone together.
St kitts and Nevis is only a quarter mil, tho I don't know what benefit that would confer unless you're coming from a country without visa free travel
And for what it's worth, UAE citizenship is not for sale directly, you have to actually live there long term
Nice table on this page: https://www.globalcitizensolutions.com/citizenship-by-invest...