How did your old coworkers not see it that way though? I get why they pushed the money at you because that's just how people are wired, bigger number equals better life in their heads. But 8pm every night plus Saturdays is basically giving up your whole life for a paycheck. You took 11 vacation days and the guy bragging about the raise has taken three, that tells you everything you need to know right there. Free time is the one thing you can't buy back later, no amount of money fixes that. You made the right call and you don't owe anyone a explanation for it.

The "made me feel like an idiot" part is the realest thing in this whole post, because every machinist has that moment where three years of cussing at tool holders gets solved by a laminated chart from a supplier with free coffee. 8,000 RPM on a 1/2 inch end mill is screaming, so yeah, you were basically sandblasting that aluminum instead of cutting it. The worst part is the math is not even hard, we just get stubborn and keep turning the dial up because faster feels like more money. I ran a 3/8 rougher way too hot for two years and blamed the spindle bearings, then found out I was just burning up the cutter. At least you found it in a free class, some of us paid for that lesson with a box of dead tools.