At What Point is the Needle Damaging Records?

Have you examined the stylus with a loop or magnifying glass. Perhaps you simply need to adjust VTF/VTA. I have my catridge (Transfiguration Temper W) more than 5 years and listen nearly as often as you do and highs are as sparkling as when I first installed it.

It may not be stylus wear but rather the suspension giving way. I don't know how to check that, but I agree with Stew, check the VTF/VTA first.

Get a loupe or magnifier and carefully examine the stylus. Sometimes you'll find dirt is the issue. A layer of grunge may have built up that does not come off with normal light brushing.

It may be difficult for an untrained eye to spot mild wear, but it's still a pretty good habit to visually check the stylus periodically.

Ask yourself which is less expensive, replacing your cartridge or replacing your record collection. I think you know the answer. You asked if you might damage your records by not replacing the cartridge now. You described the sound you are beginning to hear. Do you really need a second opinion?

That's about $00.09 a day, not bad. Buy a new cartridge.