if I've created account/wallet on coinbase or any other exchange then my account is hacked and my coins/money lost who are responsible for it
The Exchange where I've created account

80% no one can take responsible on hacking activity in cryptoworld.
is it my mistake

usually is your mistake, i can say 99,99% is your mistake, when MtGox was scam, goverman ask for an explanation of their mistakes, as well as holding customers accountable for their funds but even the mistake is Mtgox, you will still lost your money,
what's you thought about it

and how i make my account safe

on coinbase
use whitelist IP
use 2fa auth
use phone number auth
also in mail service ( gmail)
use whitelist IP and use phonenumber verification