Just like the tombs of Egypt they a prime targets of opportunistic thieves. Especially in a world where civilization has collapsed. If they have stashes of wealth like gold bars or self contained power supplies like nuclear reactors, they are even more of a target. After a few decades, intangible wealth might be lost as well. Management agencies might go bankrupt or disgruntled relatives might declare them dead and transfer all their bank accounts and property to themselves.
One Way Time Travel - Surviving Cryogenic Stasis