It is very misleading claim that bitcoin users do not need to trust centralized authority, in fact every one uses bitcoin is trusting this centralized protocol originally designed by Satoshi: Every miners, nodes, exchanges, merchants, users, no exception
One does not have to "trust" a protocol. Actually, in the case of bitcoin, there is no protocol separate from some version of bitcoin software. One can inspect that software and see in detail what it does and how it does it. One can build the software from source code if one doesn't trust the downloadable binaries. If one lacks the necessary skills to understand the source code one can hire people to do review on your behalf.
Now contrast this situation with you you face as the user of the fiat banking system, or a fractional reserve bitcoin exchange such as Mt. Gox.