The Higgs particle decays; so do most particles. Why?

Here’s an article intended to give a layperson a sense for why so many types of particles — most of them, in fact — decay away almost instantly, forcing us to discover them through various types of trickery.   This is relevant in the search for the Higgs particle, which decays away far too quickly to observe directly. (See the Higgs FAQ, the video clips from my recent public talk, or the article about recent hints of the Higgs for more info.)