This was me :) live at about 900’ flew in for work, picked up my rental Jeep and drove up to pikes peak
Didn’t get sick but could walk like 5 steps at a time before needing to catch my breath. Hung out for a bit came down and went up to Longmont. Had a nice headache for a couple days.
Second trip out I skipped pikes, but also acclimated way faster. No headache, and got in some great hiking.