You’ve seen fidget spinners, although you probably hadn’t just a year ago. You woke up one recent day, backpack stuffed with pogs, only to walk outside and see that the times have passed you by again.

Your grandmother means well. But by the time she figures out something’s a fad, it is old news. So maybe you got a fidget spinner in your stocking this year. Beats coal. Before you regift it to your ...