If you are worried about it, you can buy automatic fire extinguishers. If you hang one of those directly over the printer, I think the risk of fire spreading from that area would go close to zero.
I've made a point of buying only "quality" printers.
I have a couple of Prusa i3 Mk2/Mk2.5, and an Emotion Tech Micro Delta.
While they're maybe not the highest build quality, they're made from quality parts, with safety features enabled in software. Sometimes they're a bit too sensitive, like printing PETG with an open window, which will trigger a thermal runaway 85% of the times because the heater is unable to keep a steady temperature with the draft.
The main "fire prevention" though is i never print while not at home, and i never print while sleeping. That of course limits the time i have for printing, but so be it.
I'm thinking about upgrading to a Prusa i3 Mk3, as this supports pausing/resuming prints and cutting power between it.
