I guess it will be mainly your responsibility because it is your account. Upon registering your account it has been your responsibility to take care of it and anything that will happen to it must be taken up into you. On the other hand, the hacker do also have the responsibility because he is the one who have hacked your account just to take it into his own possession also for the sake of his own. But primarily speaking, it will be your main fault because maybe you have mishandled your account and did not take good care of the informations you have shared upon creating your account. Also, before creating an account, you must have checked first if the site you are trying to create an account is legible and a secure website. Because in most cases, intruders have been taken accounts due to the reasons that you have dive in into their trap site and filled in the information they needed to access your account. So whenever you create account, you must observe first and be able to know if the site is safe or not before creating an account. Upon securing your account, choose the most tight option on securing your account which exchanges do provide to keep your account safe. You can also ise hardware wallets to protect your assets. But most specially, you must be able to protect your account on your own by taking precautionary measures.