I always find myself assuming the person writing the comment I'm reading to be a middle-aged white male, and I feel dumb and ashamed when I realize that's not it. FWIW I'm a white male living in a western country so I'm deeply privileged/prejudiced. It's good to have my biases put in check, but I wished I didn't have them in the first place.
Edit: typo it didn't->I didn't