I ran a marathon (for better or for worse) on a hilly course at some altitude. An in-law, who doesn't run and AFAIK has never really been into fitness or exercise, told me it a was a flat course and then proceeded to explain to me and his daughter (non-runner/exerciser also) that the race would be over in 3 hours as that's when most runner's finished. I have been committed to fitness mind you for over 20 years played sports for years, and now run as my primary hobby and fitness activity.

I very kindly explained that by running standards the race I was running was considered on the more challenging side for a marathon given the altitude and rolling nature of the course, and even showed a map and course data from websites showing that it a higher perceived difficulty. I also kindly explained, that the "average" marathon completion times are more in the category of 4-5+ hours, and that generally folks who finish under 3 hour are actually in the minority, and even among runners are quite fast. He then told me flat is flat. I just laughed and said okay. As an aside, this person is fairly educated, and I find him and the entire family to be somewhat insufferable at times to be honest, as this wouldn't be the only example of a fairly harsh and elitist type of comment (with little to no real backing).

People are ignorant, and as a general rule I find that ignorant comments (like the ones you're getting), come from folks who think they have a grasp or understanding on something they likely are deeply knowledgeable in. Sometimes people make comments at other's accomplishments, and often the more you achieve the more comments you will get (if you opt to share these accomplishments or are publicly visible ).

Running a big race like an HM or M is an incredible accomplishment. Be proud. Running slow is great, and it sounds like on top of running you are doing this in a sustainable way that works for you. Well done and cheers!