I am of the firm opinion that 99% of all Chinese "diplomats","students" and "tourists" in this country are,in fact,spies...either of the military or industrial variety.Forty thousand? Never mind the IRS...call the FBI.
Chinese habit is to always carry a lot of cash when traveling. Credit cards are not yet popular, and they may not have a foreign bank account back in China to pay it. Credit cards are still not widely accepted in China outside of big cities or larger establishments.
Plus people don’t trust the government there, so they keep a lot of cash in their homes as well.
Years ago, I met a student from a dirt-poor rural part of China - probably the first in his area to go to university. He was on scholarship, which gave him his stipend every 6 months. He had 1 pair of pants, and he literally sewed his scholarship cash into the waistline of his pants - he was that concerned about losing it.
What’s here that’s even worth spying on any more?
$40,000 in travelers checks. very traceable. horrible for spies.
now, a bag of diamonds would be better. easier to sell and tough to track (assuming no laser etching).
30x gold coins wouldn’t be bad, as they’d be easy to convert. but they’d be fairly heavy and bulky in comparison to travelers checks or diamonds.
although, these days i’d imagine bitcoins would be optimal. as light as a thumb drive and able to easily receive more money from anywhere in the world. after that, it only takes a few days to convert to gold and then to cash. as more people use the bitcoin smartphone apps to trade coins for cash, the ability to move in and out of btc will improve