Unfathomable to me having so much money that you need literal warehouses for it, but even more amazing is that there was no alternative besides a 10% year over year loss on your stored capital. When you're talking about a cartel that was bringing in roughly $22Bn a year (also Wikipedia) that amounts to roughly $2.2Bn a year sunk to rats.
So, in retrospect, if you can do it legally, the Fed's bills seem like a great deal compared to stockpiling cash. And I'm sure you're paying far less to secure those, although I'm not exactly sure how these treasuries work and if you could just purchase one worth $22Bn and put it in a safe somewhere. Seems like it'd be just about impossible to steal something like that and pass it off as your own.
[0] - https://en.wikipedia.org/wiki/Pablo_Escobar#cite_note-accoun...
10% annual loss on the warehouse-stored amount does not mean 10% loss of annual income. Some of that annual income is getting turned into non-cash assets, after all.
Its talked about in Europe with the ECB using negative interest rates to (unsuccessfully) stoke their economies.
http://www.economist.com/news/finance-and-economics/21644203...
http://www.bloomberg.com/news/articles/2015-04-23/negative-i...
As an alternative to buying treasuries, you could use a bank, but keep in mind that FDIC only covers accounts up to $250k and beyond that, you're exposed to the bank's credit risk, admittedly small, but a very large concern for an individual/company with millions in cash. Banks don't work the same way for big accounts as small ones, you actually have to weigh things like "will my money be available" and "will the bank default".
If the situation gets bad enough, people will start warehousing cash in bunkers, but that's expensive and I highly doubt it could be done for less than 0.05%/year or whatever slightly negative rate the yield is on these things.
Banks provide a valuable service by offering depository safekeeping of funds. If we stay in this zero-interest environment much longer, expect to see more fees on checking accounts as net interest margin (what the banks earn between their borrowing costs and their lending prices) continues to fall.