BOS to DEN to LAX (story)

This was in December 2019. I went outside my comfort zone and flew United. What a stupid airline. I had a return trip from Boston to Los Angeles, so was flying BOS to DEN to LAX. Denver. What a stupid airport. Okay, I kind of forgot the details of this story, but basically what happened was that the BOS to DEN leg got in late, so I ran across the entire airport (DEN is huge) to catch the DEN to LAX leg before it took off, but then I had to run back across the entire airport again because they had changed the gate to the other side. So I deserve a lot of the blame for being stupid here, because I didn't check whether the gate had changed. But the reason I call United and DEN stupid is because the United staff were so snarky and unsympathetic about the fact that I was at the wrong gate. Rude. I got in a lot of cardio that day