Even if a cupcake is perfectly safe, it might taste like cardboard after a day. Staleness is the real enemy of happiness. If you leave a plain cupcake out, the moisture escapes into the air, and you’re left with a dry crumb. That’s why bakers store them in airtight containers, not just out in the open.
I once left a batch of red velvet cupcakes on the counter overnight. The next day, they were so dry they crumbled into dust when I tried to eat one. A tragedy of epic proportions. Now I always wrap them in plastic wrap or use a cake keeper. Your future self will thank you.