I experienced this same failing of hydrometers for myself in 1971...you would have thought that they would have improved in quality somewhat in the last 30+ years
I will say this tho...you can buy a hydrometer now for the price of a couple of hamburgers (or one really good beer). Back then, for a poor college student anyway, breaking one meant you were gonna go without eating for a couple of weeks...either that or sell your 55 Ford
Just tie a rock to a stick with lines on it... calibrate it in the local lake, and you've got an unbreakable hydrometer... sample size may be an issue...
Hydrometers actually have a bad rep in labs because they are constantly bonked on the rather thin glass at the tip... over time, it seems to weaken and fail unless extreme care is taken... one way is just to keep the hydrometer floating at all times, but that of course means you have a rather tippy tube full of water sitting around.... luckily, they are cheap.
i found out that if you try and just pour out the wort from the theif with hydro meter still inside you its neck will break when it hits your porclien sink!!!
I'm really lazy about using my hydrometer anyway. I guess this is set to change with time. I mean I started brewing beer five years ago but only recently started on the AG approach. But yeah, the hydrometer is def. a fundamental piece of apparatus if you want to get involved with the technical side of homebrewing.