I was surprised at how many need over 2 million to be FI....so many variables. With no mortgage, no debt, simple lifestyle, some defined benefit, I am FI with a good bit less than 1 million.
It all depends on your current, plus anticipated future needs.
DW/me are certainly outliers in this sense. We not only have to account for ourselves, but also for our (disabled) adult son, expecting him to live 2+ decades after we both pass.
For the personal care he will need (which we provide now), it will be very expensive to replace with a person paid to perform the same duties, several days a week.
Unfortunately, public resources are grossly inadquate to take care of him and his needs (been there, done that over the last decade), so we decided to take the private care route. Before anybody asks, no - we don't have any family members who will take on this "job". Anyway, since we need to account for possibly five decades of care for him (assuming DW/me die tomorrow), we have no idea of who will be around to take on the responsibility. That's why we chose to have "institutions" handle his trust (three different partners - lawyer, investor, and commercial trust management), each with their own documented responsibility, and "separation of duties".
Expensive? Yes, but that's life. Like the Stones song says, "you don't always get what you want, but if you're lucky you get what you need". Luckly, we feel we can cover both his/our financial obligations many years into the future.
Heck, it's only money...