I thought about this but its all about balance, money spent in your 20s and 30s is more valuable than in your 40s. That doesn't mean don't save at all just be balanced with a slight tilt towards saving more.
Most of the people doing FIRE are not the types who spend money on expensive stuff. If they were, they’d be doing fat FIRE (uncommon). Most people doing FIRE do not have high standards of living. If they did, it’d run somewhat counter to FIRE. The people who can do fat fire are just lucky and got rich and should be ignored promptly.
There is also the problem that many bought real estate far before it was as fiendishly expensive as it is now, bought stocks and were part of companies during wild bull runs, and act like you can reproduce their success trivially. (You can’t)
Also, I think of spending in your youth as an investment in memories. What is the point of getting all your best trips in at 65 (just before dementia sets in) when you have at best 30 years to enjoy them. If you did the trips when you’re 30, you’d have decades more to enjoy them and could actually go on them. Living for when you’re senile is a scam.
I socked away and invested everything I could during my career in Silicon Valley. I retired just a few months after my fortieth birthday.
Why most of my colleagues didn't do the same and instead 'leveled up' their lifestyle to match their income is beyond my capacity to understand.