even if you are using a hardware wallet there is still a chance that you can experience a problem. Like for example what of you did loose your hardware wallet ? Or what if it is get damage by water, fire , sand or you accidentally drop it and it got shocked resulting for you to loose all you data inside it .
you can also get hacked or phihsed whenever you insert your usb ( hardware wallet ) and paste your private keys to any exchange .
See? Almost every action do still have a risk . so whether you use hardware or online wallet , their security are both the same .