Recently ER'd. Question is very open-ended (perhaps intentionally), so really depends how I look at it. In terms of one year of income, the "loss" would be upper six-figures. In terms of lost opportunity in wages, stock options, bonuses, etc. relative to working a handful more years (as had originally intended), the "loss" would be several million.
First few days my brain was kinda split:
Left Brain: "Whoa! Dude, what did you do? Did you really just walk away from that much money? WTF? You really need to consult me on those kinds of decisions"
Right Brain: "Hey, leave him alone. He's had enough. You know they weren't treating him very well and he needs to start living life and smelling the roses and stuff."
LB: "STFU, you don't know what you're talking about. He loved that career. Look at everything he's accomplished, now he's leaving all that on the table."
RB: "Well, he can't take it with him. That job probably already shaved a few years off his lifespan from the stress and sleep deprivation"
LB: "So, what. He's not gonna wanna live if he's poor anyhow"
RB: "He's hardly going to be poor. You're just being hysterical"
LB: "What
You calling me hysterical? You gotta a lotta nerve. You do know I'm the left brain in this picture don't you."