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

is it my mistake

what's you thought about it

and how i make my account safe

Banks had the same issue years ago. At the time they had no specific policy of who was ultimatelly liable. Its still a grey area. Unfortunately when you are dealing in a market proud to be unregulated you cant expect or probaly receive protection. There are some more trusted exchanges out there but its the issue in the industry IMO.