I thought the wallets couldn't be hacked.

He has a 30% success rate. That's pretty high.
The rate will be higher if you do not add antivirus on your computer? Why ?
there are many ways to hack the wallet including a virus or malware if you do not have antivirus on the computer
surely you will not know if your computer is infected superbly and all your data can be retrieved by a hacker so be careful