A friend of mine used to always say how squatting wasn't bad for the knees. She did powerlifting for many years then OLY lifting and I heard her complaining the other day that she could't even do a squat now because of all the pain that she had from the OLY squats (and the couple of years powerlifitng too I'm sure).
I've been training harder and longer and my knees are feeling great at the moment. I squat 4x a week and do events as well.
Raimonds Bergmanis was in the Olympics 3 times representing Latvia in the OLY competition. He is also near 40 years old and a top 10 Strongman who is known for competing raw in the events (no belt straps wraps suit, etc...).
You just have to take care of yourself.