I'm somewhat in the same boat conceptually, though I'm in my early 60s and will retire a year from now. Wife and I have been extremely frugal our whole married life, zero debt, pensions and good SS coming, and a very healthy nest egg that given our lifestyle, may not have to be tapped into until RMDs in my early 70s. BUT, given my mentality and past lifestyle, I am going to have a bit of an adjustment at retirement, allowing myself to spend and be less frugal, to really enjoy retirement and loosen up the purse strings so to speak. Sounds kind of strange, but that's where I am. I guess it's kind of a good place to be, better than not having enough or having to work a lot longer because of a shortfall or being unprepared financially.My wife and I are into "FIRE" and it has been good and also bad.
I'm currently under 40 and plan to retire at 55. We've technically reached "FI" but "RE" is a different part of the equation. We also set a retirement number but each milestone we hit that number gets bigger.
Until I turn 40 we're keeping our foot on the gas for savings and after that we plan to relax a bit. Go fully remote with a more relaxed role and moving back to a home town in the mountains. Focus on the cruise control portion of the ride instead of accelerating wealth like our goal has been the past 10 years.
My personal downside to FIRE is that I'm incredibly focused on numbers. Even though we hit our "FI" number I haven't been able to adjust my mindset and spend more. I'm worried if I quit any earlier than 55 I would be stressed about the money I wasn't earning. I am not sure if I would get bored, but I sure as hell would be thinking about "if I worked one more year I could buy this much more stuff or make this much more money"