From https://tezos.com/dispelling-bitcoin-myths.html

Myth #1: Satoshi solved the Byzantine Generals problem which was thought impossible to solve!
Fact: The consensus problem isn’t that difficult, it’s about who’s allowed to take part in it.

Myth #2: The proof-of-work system is great because it incentivizes miners to upgrade their equipment, thus a lot of computing power is powering Bitcoin.
Fact: These upgrades do nothing to increase the transaction processing capacity of the Bitcoin network.

Myth #3: Bitcoin is a math-based currency is backed by math.
Fact: Bitcoin is based on a clever set of incentives.

Myth #4: The proof-of-work system is completely decentralized
Fact: Trust is still involved in the system

Myth #5: A decentralized system is safe
Fact: not necessarily

Myth #6: The Bitcoin ledger is just a technology, it has nothing to do with politics.
Fact: Proof-of-work crypto-ledgers are primarily designed to withstand attacks by governments. It is the only advantage of a proof-of-work decentralized crypto-ledger over a centralized or polycentric one.