Burning your toast and having to remake it might cause a five-minute delay that saves you from a larger negative event, like a car accident or a missed important encounter.
To prevent future burning, clean your toaster at least once a month (or weekly if used daily): Always disconnect the power first. Burnt Toaster
While burnt starchy foods contain acrylamide (a "probable carcinogen" in high doses in animal studies), current human research shows no strong link between dietary acrylamide and cancer. Burning your toast and having to remake it