Be in a country with the rule of law.

Structure things so if they betray you, they have a very high chance of getting detected and needing to go on the run - e.g. access control records, CCTV and whatnot.

Then hire guards who would have to sacrifice a lot if they went on the run permanently. e.g. guards with partners, school-age children, extended family nearby, friends, and community ties like membership of voluntary organisations, churches or clubs.

While that sound smart and plausible, I would assume that there is some solution to that problem, otherwise how would private security work at all?

A security guard selling the Mona Lisa has to figure out how to get rid of it. Bitcoin's quite a bit easier in that regard.