I don't understand why someone, with some technical education, would use any chromium based browser instead of firefox, any ideas?
Safari isn't Chromium (it's the opposite, Google forked WebKit and they've diverged). But that's not really your point.
There's a lot of reason to use Chrome: deep integration with Google (privacy issues aside, it's really useful), better add-on dev ecosystem which leads to better add-ons, WebKit was far ahead of Gecko for a while, I personally prefer the devtools in Chrome, developers tend to verify their website works more in Chrome so fewer bugs, iOS is webkit-only, etc.
Firefox is a great browser, especially now. But so is Chrome.