I use it for re heating food, it's a good way to save money and energy. This way I can batch cook and eat foods I made myself later instead of relying on convience foods. With a disability, that's quite vital. I never use it for cooking though, not for anything except melting butter.
I also know how to re heat food without a microwave, I did for years before I met my husband because I couldn't afford to buy a microwave being disabled and on benefits. For example leftover pizza I reheat in a non stick pan or an airfyrer, not a microwave. If you don't have a microwave bain marie is always an option to reheat food (put a pot of water on a stove, bring it to a boil, add a bowl on top and heat your food in that).