I'm pretty sure competitive advantage plays a role. Looking at myself and most front-end devs I meet, we tend to use Chrome as a primary browser in part because of the dev tools.
In my case I remember there was a point where I preferred Chrome's dev tools over Firefox' built-in dev tools as well as Firebug, and that played a role in my use of Chrome as a primary browser. Things may have changed, but here I am still using Chrome.
The downside is that I need to remind myself to properly test in Firefox and Safari and, to my shame, it has happened that I entirely forgot and the testing department ended up being that reminder.
Also, Could it be that another reason for dev tools' existence might be that browser developers use it themselves?
In my case I remember there was a point where I preferred Chrome's dev tools over Firefox' built-in dev tools as well as Firebug, and that played a role in my use of Chrome as a primary browser. Things may have changed, but here I am still using Chrome.
The downside is that I need to remind myself to properly test in Firefox and Safari and, to my shame, it has happened that I entirely forgot and the testing department ended up being that reminder.
Also, Could it be that another reason for dev tools' existence might be that browser developers use it themselves?