Think about it. The fact that we are relying on a public information with a twist to be secure is not the answer.
-snip-
For me it comes down to "trust" (as much as anything can be trusted) of the tech or trust of people (those that run master nodes, mixers etc). Everything has the potential to be cracked or exploited at some point but given human nature, I'd rather trust "tech" over people any day.