Do you think my camera (a Panasonic Lumix from about 2009) is harming the SD cards? Or am I just buying cheap cards and should spend more to get good ones?
I guess it is possible that your camera is corrupting your SD cards, but I’ll be prone to suspect the cheap SD cards instead. I know they are less expensive than name brand ones, but they are more risky. SanDisk and Lexar memory cards are better options, in my opinion.
Also, although name brand memory cards offer better reliability, it doesn’t mean they’ll never fail. There’s nothing like backing up your pictures on your computer regularly.