If FireCalc gave a probability at which I wasn't comfortable, then I'd not retire. Period. If I lost my job and unavoidably retired because professional employment was not forthcoming, I'd drastically lower my spending.
But you're quite right, that ultimately it isn't about math... it's about feelings. If at the final stage of life, you regret the experiences not enjoyed, because of reluctance to spend money, then of course, it behooves you to take the risk, to pursue the enjoyment. If on the contrary your future-self will relish with glee and self-satisfaction the accumulated and unspent stash, then... we have the contrary conclusion.