It’s very unfortunate this happened Unfortunately, there are so many different attack vectors with all devices and wallet types, be it software, cold, and hardware… some just tend to be more secure.
Sometimes it’s really hard to figure out what happened.
Crypto is still in its infancy stage and the responsibility at this moment is mainly on the wallet owner to be very well informed about security risks and to try to mitigate those using best practices. At this stage, it is very easy to lose everything if not super careful. I know this is not of any help to you now…
Unfortunately, there are so many different attack vectors with all devices and wallet types, be it software, cold, and hardware… some just tend to be more secure.