No doubt. The town of Chamonix is at 3,402 and the highest lift served skiing is at 12,605. Unless you stay at one of the high mountain huts like Cosmiques or bivouac you are always coming back down. When I went to 15,777, from the valley, I spent four nights at progressive elevations.
I was living clean in Breckenridge, no booze. I lived there for a month and skinned up the mountain every day. I don’t think it was the first night, maybe it was the second and third when I got sick. Absolutely crushed, couldn’t do anything. Also, slept like shit the whole time I was there.
While I was there, my ski buddies from NY went to Telluride so I drove from Breck to meet them. We got seriously hammered, I remember it very well because it was the Super Bowl when the guy caught the ball on his head for the win. Apparently there’s lots of beanheads that go there because the bar we were in had a huge green wall. People were not happy, but we were. Almost had to fight our way out of there. Went to Silverton after that all hung over and hiked at altitude with no problems but my buddies who had just flown in were hurtin’ for certain.
Feeling the effects of altitude and getting altitude sickness are two very different things.