Bitcoin is all about decentralization and hence there is a distribution of the responsibilities too. There is no central authority to take care of your funds and even if you are keeping your funds on any exchange, there is no guarantee that you will get your funds back in case of any hacking attempt. However, Bitcoin as a technology is very strong and no one can steal your funds if you are taking enough security precautions. Keep your funds with you (offline) and make sure that you are following security guidelines.