Why do hand held can openers stop working so quickly?

Truth of the matter is cheap ones don't last long, expensive ones also bought at certain stores may not last long just because they are expensive. My advise, go to a restaurant supply store, see what they have and ask questions. I bought one for $150 US and it's worth about someone paying me for the aggravation of the time spent to figure it out how to use it. It's one that the edges don't cut anyones fingers also don't open cans. Go and get something priced about $20-25, good grips, easily washed, not to heavy and WITH a return policy. I bought 6 now, and due to the earthquakes and loss of electricity I have in my area, it's been great for everyone I gave it to and I use it instead of an electric can opener. My Mom, who just left me to go to my Dad in the Heavens, bought the best electric can openers in the world 46 years ago, and although one is ugly green and the other ugly gold, popular 70's colors, those 2 can openers even have little things on the bottom to make them taller for bigger cans. You can't find them now, they even have good knife sharpeners on the side. Anyhow, restaurant supply, good handles, ask questions, good return policy. Good Luck!

Can openers do break.

But if they're breaking quickly, then I'd suggest you're buying very cheap can openers.

One of these should cost $10-20 and should last at least a year.

The fact of the matter is they dont make them like they used to. I had one my grandma gave me in the early 80's.....and for some god awful reason i cant find it any more....it always worked ALWAYS! Never had an issue...They dont make them to last anymore...it just leads to more profits for the kitchen essentials market. hit yard sales...second hand stores or even online second hand places. You want one that wont stop working...buy one from the 60's-80's and you wont buy another one.

It's really easy to cure generally. The main cause, be they cheap or otherwise, is the non forced roller cog (not the one attached to the twister, but the one that sits below the circular blade) siezes up with rust. A vigorous blast with an old toothbrush, then undo the Phillips screw and remove. Carefully pull the blade and cog off - remember it's meant to rotate so if it's still stiff use a small pair of pliers and rotate it until it's lose and free. Pull the blade and cog off the spindle as mentioned and clean all parts quickly with the brush. If you have some WD 40 spray a bit onto a paper towel and then wipe the spindle with the towel. Reassemble. Should work a treat. I've literally just done this to a siezed can opener and it works like new. Took 3 minutes flat!