I don't want to end up like my in-laws. They retired in the early 1990s at 60 with a little over $1M, which I'm sure seemed like a huge sum back then. They had a decent non-COLA pension and took SS at FRA. MIL's SS was insignificant since she only worked about 10 years after the kids moved out.
They are now 85/84 and health is not good, but not bad for their age. Their only assets are $150K home equity, an old car, and about $90K in an IRA. They live modestly on SS, RMDs from what's left of the IRA, and the non-COLA pension, which now seems minuscule compared to when it started. The savings are barely enough for one year of LTC for one of them, if needed. So DW and I worry about that constantly.
They traveled the world extensively in their 60s and 70s and lived in a very nice house on the Florida coast. FIL went back to work consulting for a few years after they realized the burn rate was too rich for their resources. They now live nearby so we can help them, and they are increasingly dependent on us for everything. If/when they run out of money, all the burden will fall on DW and myself. DW's only sibling is in no position to help and lives in another part of the country.
All my retirement planning is based on having a certain sum leftover at our actuarial life expectancy. That amount should be sufficient to cover any of the risks typically talked about here: runaway inflation, LTC, longevity. Hopefully, we won't encounter more than one of those. Above all, we don't want to be a burden to our kids. And if none of that bad stuff happens, they will enjoy a nice inheritance.
So yeah, I'm in the 95-100% success-rate club. And after 3 years of retirement, we're still only spending about 70% of what FIRECalc says we can at 100%. That's largely a result of all the uncertainty surrounding the in-laws, which is not something I specifically planned for.