Bitcoin has been impressive in a lot of ways since it's beginning but the one thing that blew me out the most was the ideology. A foolproof peer to peer online transaction system based on blockchain technology was just a beautiful set of works executed and implemented by Satoshi and no wonder it has already made its mark in every field it is being used in.
The protocol may be foolproof in some ways, but when you have people spending 1 BTC out of a 8000 utxo and paying a 7999 BTC fee it makes you wonder.