I'm a fan of these cautionary tales. I'm on the record as thinking that there are a good number of people out there "doing it wrong". Maybe even some in this community.
Would you mind elaborating on that? I may be one of those people -_-
Sorry, I'm just now seeing this. I'll do my best.
1.) Most people's lives don't map 1 to 1 to those of the most successful FIRE bloggers. There is a limited demand for lifestyle porn on the internet and you shouldn't bank on blog income. Basic stuff. People understand this in the abstract. But most of the bloggers are also probably type-A go getters who can't help but to make money.
Honesty is necessary. Honesty about whether or not you're that kind of person, or say, someone who clicks around on the internet at the office a few hours a day instead of putting in tangible work towards the next big raise. I'm personally not a go-getter on the level of MMM or even some of the more forums famous faces around here. So I factor that in.
Also, a blogger's spending (even if they're being 100% honest and transparent) probably doesn't capture the tangible and intangible benefits of being a web celebrity or thought-leader.
2.) "Income doesn't matter; only spending" doesn't scale to the lowest levels. You have an inelastic demand for things like food, shelter, and life-saving medicine. You can make a concerted choice to live on $10 of coffee a year instead of $1000 of coffee a year. You can't as easily elect to pay $1,000 for world-class cancer treatment instead of $100,000.
People have their plans for medical, and that's all well and good. But a healthy bit of observation shows that the majority party in the United States is trying to defund and destroy public health programs at every level. Or that a wave of nativism in other desirable countries has actual and would-be political leaders championing the tightening of immigration. Maybe that's not a problem if you're retiring well into the seven figures. Potential lean-FIRE expats may be less desirable though. They could find themselves searching for a social safety net that is willing to catch them.. I truly don't know where we're heading over the next few years.
3.) You at 30 is not you at 40, 50, 60, so on.
People change. I'm young, tough, strong, and healthy. I can deal with considerable amounts of bullshit. But stuff happens. A buddy of my tore his ACL playing basketball. He's 29, healthy, active, and recovering as well as can be expected. But that's a risk factor for early-onset arthritis. Will it stop him from leading an active an fulfilling life? Probably not. But it could turn what would be 15 miles a day walking around a new city into half that with a few $30 Uber rides. Back problems can cause you to upgrade from slumming it in hostels, to a hotel with a reliably suitable mattress.
Attitudes change too. You may love the grind now. But eventually it wears on you. That's why it's called the grind. My parents/are boomers. As are their siblings and friends. They spend lavishly on entertainment and comfort in their 60s. Decades ago, they were anti-consumerist hippies who subsisted on cheap pot and free love.
That covers most of it I think.