The only problems I've ever had with speakers were tweeters blowing out. It actually happened to me a couple/three times. With my Celestion SL600's and my KLH 17's. I never played my stereo very loudly so I have no trouble blaming the componentry. And then there were several times when ultra-weighty "audiophile" speaker cable pulled my petite mini-monitors off their stands onto the floor. More than once it resulted in speaker cabinet dents & dings. For a while I'd rope speakers to their stands with twine. Now I use Quake Hold Museum Putty.
How long does it take a decent quality speaker to "wear out"?
After all, they do have moving parts and capacitors. . . .
(I suppose that "decent quality" s a relative term. FTR, I am running a pair of the older B&W 805s, and for all I know, they may not actually meet the criteria of "decent quality.")