It doesn't wait for old age.
The people most likely to be caught with nothing in place aren't the old and the ill. They're the young and the healthy — the ones who never thought to.
Terri Schiavo was 26 when her heart stopped. She got a heartbeat back, but never regained awareness. Because she had never written down what she'd want, or named who should decide, her husband and her parents spent fifteen years — and a national court fight — trying to speak for a person who had left them nothing to go on.
It wasn't a failure of love. Everyone in that room believed they were fighting for her. It was the absence of a single, twenty-minute conversation — the one where she could have said, in her own words, this is what I'd want, and this is who I trust to say it.
She was 26. Not 86. That is the whole point.