Altitude sickness on Aconcagua

Aconcagua is the highest mountain in the world outside of the Himalayas; typical expeditions take 2-3 weeks to summit; I attempted to do it in 4 days. But after hiking for 14 hours the first day until 1am and still not getting to base camp, I had a feeling about what it was going to be like. Unlike every other expedition my climbing partner (who was crazy enough to go with me) and I opted against renting mules to carry our gear to base camp, so we carried about 80 pounds each up the seemingly endless and aptly named "death march" to base camp. What fun is climbing if you need mules to help? There we had a medical check and my O2 sat was only 73. That's lower than most emphysema patients! But would that stop me... of course not. We headed up to high camp and planned to summit 2 days later. But on our summit day we woke up with terrible headaches and severe altitude sickness. Such was our limit; we headed down after only reaching 6,000m. With more time it would have been a cake walk, but what fun is a cake walk when you want to live ultra-ridiculously?