Even tech savvy people can still fall for that stuff unfortunately.
The number of things it is truly appropriate to say this about approaches zero. Matthias has extensive "computer" experience (and that's an understatement). It's counter-productive to no-true-Scotsman the concept of a person who is "competent" or "savvy" with "computers" - the field is too large/complex, especially anything remotely security related. Just focus on reality, i.e. what actually happens. This happened.
Give any of us a tired morning without coffee and a mis-click, and many of us could be in the same predicament.
If his channel ever comes back, check out the cool wood projects incorporating a Raspberry Pi.
But you would be surprised how much you drop your defenses when you are convinced you just got an email from a friend/business partner/etc.