Some Logitech mouse switches have been known to fail in normal use.

At least one person has put together a good overview of what they think is happening: https://www.youtube.com/watch?v=v5BhECVlKJA (details in video description)

They just fail. Particularly the office mice don't last very long for gaming (orders of magnitude more travel and clicks)

Use cats. For all great Logi ergonomics, they fall prey to cat hair; and pads cover the screws, so they can't be reassembled pristine after cleaning. Still, M500s is the best.