I don’t know if it also happens to you, but I always have this fear (not only the equipment but also the whole freaking house).
I have two Synology NAS devices and one “custom” server (just a PSU, a Ryzen CPU, two RAM sticks and a SSD).
Everything is grounded, on a compliant safety electrical installation, but I don’t know… I’m maybe paranoiac by nature.
My biggest doubt is about the PSU. It is a certified PSU (from Be Quiet! IIRC), that has more than enough power (500W).
I have everything on UPS’s, my Synology NAS contacts me if there’s an issue, etc. My fear of fire stemmed from being out of town when a co-worker texted to tell me my apartment building was on fire. Luckily, my unit was fine, but not so the people in back. The fire was started by idiots smoking on the rooftop deck. After that I installed cameras so I could see what was going on. But I don’t worry about my equipment per se. As others have suggested, there’s all sorts of things that can start a fire, large appliances, hot water heater, wiring in the walls, flames from the house next door, burglars, arsonists, plane crashes, ghosts, zombies, etc. You will never be safe! Bwhahahahahaha! Happy Halloween!