Most of the folks on this forum are conservative and few retire the minute they hit their FIRE number. Most also overplan SORR mitigation strategies.
For example, many FIRE with a large cash fund equal to 2-3 years expenses, have multiple income streams, have multiple (lean, full, fat) FIRE budgets that they use depending on market conditions, have buffers built into the FIRE budget that they used to calculate the stash needed, etc.
Totally true for us as well.
Even though we are between 3.25 and 4% withdrawal rate based on our current spending, we've made some adjustments to make us (me, since I do most of the budgeting and calculations) feel more comfortable:
1. Moved ~2 years of spending into a high yield savings account to manage immediate SORR.
2. Came up with a barebones budget that would be just about covered by dividends alone.
3. Realized at the base budget we would be spending so little that our 2 years of savings accounts alone would last 3 years. The other bonus- health care on the exchange would be essentially free at that spending level, and we'd be paying essentially no taxes.
4. We have a paid off house.
5. Citizenship in a country where we could cut costs another 20-30% off our base budget. I'll get a modest pension in less than 5 years that would almost completely cover a decent, if frugal, living there- even if we had no other income or assets.
6. I still work part-time, just to stay busy and social. I don't even spend all the money I earn as my "fun" money.
I know all of this is statistically complete overkill, but the paranoia wants what it wants. I know that I sleep well at night.
In reality, it's likely you won't feel comfortable until you have practical experience that it works a couple of years after you stop work and start living without regular work income.
The only thing I'd suggest is if you don't feel like you can jump comfortably in, give yourself some baby steps. Set up a plan for what a few years of spending on your "emergency" budget would look like. Not "I'm not going to starve" budget, but "this is nice, but just missing most of the frills" budget. Then actually live on that budget for a few months. Heck, if you've been saving diligently, you might already be there! See how it feels.
Once you realize that your "worst case scenario" is actually perfectly okay, you're golden. Make sure you have a couple of years relatively liquid (high-yield savings, CD ladder, etc.) at this level and FIRE whenever you want without regrets.
Also remember when running all those FIRE simulators: If you hit 100% back-tested spending level, that means your savings would have survived *every* market downturn. So if you could have had a 100% chance of success even if retiring in Sept. 1929, I think you're pretty safe today no matter what you think about the current state of the market.
I think it's also super important to remember that your savings would have survived *every* market downturn ***without changing a single thing***. No selling eggs from your chickens and making an extra $75 a month. No postponing a vacation or downgrading to a local drive instead of an international flight. No driving your car a year longer than planned or going to meatless meals one day a week. Nothing at all done, even ifn the face of economic catastrophe.
In reality, who would actually do that? Unless someone has ZERO fat to trim, they are making changes. And even if they have zero fat, they are looking to walk someone's dog for $20 a week, or getting a job once there are jobs to be had after the economy recovers, or something.
I do wonder how many people would have had the fortitude or discipline to hang on during the great depression as thier portfolio when down from $31.30 in September 1929 to $4.77 in June 1932 an 85% drop in a grinding 3 years - but like other crazy times (2000, 2007, 2021, maybe now) there was a runup before then a fallout after so maybe if they were in it on the way up then then they get back to par. Anyway changes can be made for the good or bad.
I doubt I would have, if by "hang on", you mean "change nothing and white knuckle it, hoping for the best". But for me, that's kinda the point. If the SHTF, I won't just hang on. I'll make changes--some in spending, and maybe even some in earning. Even if I can't find a side hustle (or FT job) in April 1930, I cut what I can, and maybe I get a job in 1935 when things have recovered a bit, to allow my portfolio to recover a bit, too.
That's not a failure to me, if it happens. It's just life.
I'm not doing NOTHING AT ALL different than the status quo. No one is.