your way of going at it is wrong. you are basically saying just because bitcoin and banks are using the same cryptography it makes both of them safe. but you are wrong.
for example look at bitcoin gold, the most recent embarrassment of altcoins. it is using the same cryptography and even more it is a fork of bitcoin. but it is not at all safe. there was a successful 51% attack recently.
what makes bitcoin safe starts with the cryptography and then is followed by a battle hardened system that was tested and attacked (failed attacks) for 9 years. it is also safest because of all the hashing power that goes into generating a new block.