On the other hand I bet you have a better life with your belief until - if ever- you learn the difference the hard way.
Take the simple question: can you look at personal data on your monitor? What about Van Eck phreaking? Basically you are broadcasting the data. Do you need to protect against that?
Tell me what GDPR says about that.
It's like worrying that someone will be struck by lightning because they're located on your property near an antenna you set up, and you'll be charged with murder because of that. Yes, it's possible, and about equally as likely.
[1] https://en.m.wikipedia.org/wiki/Van_Eck_phreaking#LCDs
I would estimate the frequency of the attack similar to Lightnings killing people. I’m quite sure it happens but only in very small scale because you have to get so close to the victim.
If you choose to display customer data on your screen while raising funds for launching a new cryptocurrency in the Sultanate of Kinakuta from sketchy Chinese generals, it's on you.