Do I absolutely have to eat GF or is this a choice? For me personally it's a little bit of both. My mom had me on a GF diet when I was younger as my youngest brother & I have Autism. She heard that the diet could help us (not cure us, just be more comfortable). Of course in the early-mid 90's there were not as many options nor were they tasteful, and as picky eaters as kids, we didn't like it. She gave up and let us eat our own ways. A few years ago when I was living on campus at a college I was attending, I started noticing that every time I ate I always was extremely bloated (even if it wasn't a large meal), exhausted, had stomach cramps, diarrhea, couldn't concentrate or remember things, and just feet like my body was holding on to everything it just ate instead of digesting it (I gained a lot of weight and could never lose it). After months of this happening & moving out into an apartment, I slowly started to see the foods causing the most problems had gluten in them. I decided to try going gluten-free just to see if it would make any difference. While it was difficult to resist "glutenized" foods at first, it got easier. I noticed a lot of changes within the first 10 days and the next time I went home to visit my family, my mom noticed too. I had more energy, was more alert, I didn't have intestinal problems as much, and I was actually losing weight. When I went for a check-up at the doctor a couple of months later, I had lost 10 pounds by then but was more healthy. I told them about my GF diet and why I did it. They decided to test me for Celiac's, which of course came back negative. I thought it was pointless they tested me since if I was pretty much clear of gluten for 2 months, they're not going to pick up on it. As such, I never went on an all-gluten diet just to get it done again. I know my body is MUCH more happier being gluten-free and just assume it's an intolerance.
Since it is mostly a lifestyle choice, at times I am super careful and others I just do my best. When I first started I was extremely diligent for the first few months - separate pans from roommate, no restaurants. However this made me get bored quite quickly with food options - I felt like I was in a "rut", only having so many meal options and recipes. I wasn't much of a cook before so it was harder to add variety. When spring came around, I started to be lax. I'd have a piece of food that had some amount of gluten in it here & then. Eventually that grew into one thing a few times a week to once a day to a few items a day. Because it was slowly building up in my body again the changes weren't as easy to detect, until a couple months later when I noticed I put on weight, was having stomach problems every day and I even looked bloated in pictures!
Since this summer I've been balancing between an all-or-nothing approach. Now the majority of my food choices are gluten-free - 90% of the time I will deliberately choose gluten-free options. 10% of the time is having a bite of something a friend baked or cooked to "try it", or going out to eat and ordering something that would be gluten-free but realizing there is cross-contamination from cooking. I realize those with Celiac's that this isn't possible, and at times I DO notice the cross-contamination or gluten a couple hours later, but I try to make the most and best of what I can in the environment I'm in. It's part lifestyle choice, part necessity. These days I have more of a firm mind-set that it is now a necessity, just for my own health reasons. I think those who do it out of choice are probably trying to see if it would benefit them or a loved one in some way, and as long as it does help others feel more comfortable and peaceful in their body, that's all that matters.