Good points about personal oxygen needs. If you have never been that high - you don't know.
Where I grew up in GA a lot of my friends got pilots licenses before we graduated high school. One friend, a doctor's son, told me he couldn't go above 10,000 ft without oxygen or else he would completely pass out.
Something to be aware of, so that if you start feeling funny, you know to take it seriously.
Merritt Island, FL
When a person asks you for advice, they don't want advice. They want corroboration.