Grabs notebook and pen to furiously write stuff down
Lots of good ideas already in the thread
For me, I probably don’t destroy gear as often as I should but how I handle it is making specific monsters, environmental challenges, and crit abilities that target gear every now and then.
Not every monster will destroy gear. But to add variety and make certain monsters scarier, I’ll give them an ability that destroys gear. A party just came against a giant and his Smash ability deals damage and destroys gear. The fish men, like Rogue said, will steal your weapon. The captain of the guard is trained to bash in your shield and armor to lower your defense. If I include narrative reasons into my monster’a mechanics, there’s never really a question of why a player’s gear is destroyed.
Environmental challenges also provide great excuses to break stuff. When players are running through a forest, their gear is probably safe, but while they are exploring a volcano… you can bet their gear is in danger. In scenes that make sense, I’ll drop something in the environment that might break gear. Lava, falling rocks, acid, tangled webs and vines, oozes, etc… Again, the environment becomes a lot scarier when it starts taking away your stuff and narratively it makes sense.
Then finally, and it sort of goes with the monster one, I will often note a specific crit ability for enemies that may include breaking gear. On Nat 20, smash one piece of random equipment. For some bigger bosses they might crit on an 18+ or even a 15+.
I just see breaking gear as another tool in the toolbox that I can add or take out to tune challenges for my players.