I have been that hardcore one too, for years, untill these last few years. I felt fine that way except that it limited too seriously my social life. If I ate out, teh options were part of this salad and part of that salad, and still get sick after, and a lot of attention is drawn to what is and what isn't on your plate. I felt fine the way I cooked, more towards 'living food' and raw food - but I cut slowly back. The social life, its limiting it, was the number 1 reason.
I cut back, and have sometimes a bit of cheese, sometimes a bit of ice cream, sometimes even fish or seafood, on special occasions. I still don't drink milk (it'd not the most compatible thing on this planet with my stomach), and more often the cheese is .. a spoon of grated sheep cheese than anything 'normal'.
I did felt very good as the hardcore vegan, and it feels sad to say that the social life was mostly the reason of being back to more 'normal'. It was too high a price for feeling physically good to be isolated by food, so the extreme hardcore can limit the life as much as an eating disorder. I needed social life, without being sick every single time afrer eating some cooked food too. (There have been periodical returns to that path. When I get too sick, that fixes it. But unless you have a family and friends that all follow that way of living and eating, and support you for 100 % on it, it is hard.)
Would I be more sick, I'd return there again. So I am something in the middle of the ways. I spent nearly 15 years being afraid of eggs (I could not decide morally if they were ok, now I eat sometimes egg whites), casual milk, fish... those, of the social point of life, can add another aspect. You go out say with your friend or your family, and they don't have to feel they are in a 'cow restaurant' (where everything edible they'd see on the menus would be salads, green, green, green) and you don't have to have that much struggle every single time.
I should add some weird allergies to the limit list. Onions. Plus add gluten free to the list. Makes it still an adventure to find anything, but hey, it is life. People need social life, and it's sad when the food limits the options too much. Luckily the people around don't find it a big issue me not eating meat [including chicken, hams, bacons etc]. And it can help you feel better when you have around you people who like the food you do - say in this case mostly vegetarian food, ethnichly mixing (something south European (Sicilian), something Brazilian & Argentine & other South American, and something Japanese combined in art), and with a lot of spices. Cooking can be fun - but it needs normally 2 people or more to cook for, to make it more interesting.