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

Most of the hacking incidents are happening due to the users' negligence. Although, sometimes cryptocurrency exchanges got hacked by the hackers themselves. But most of the account hacking is because the users are using less secure passwords and not using 2FA. sometimes is from the exchange side where the hackers will hack the exchange wallet itself.