I've only cracked one. I didn't even notice the scuff and crack on first inspection and continued to ride with it. Damage was less than the pictures shown above.
I had taken a corner too fast on glass-slick dry pavement and skidded a few feet on my face. My safety glasses were also scuffed yet kept my eye safe from harm. My face had some pretty road rash.

Anyhow, the damaged helmet was given some kind words and was promptly replaced after noticing the damage. It did it's duty as designed.

I've also retired 2 others.
One had been kept in the garage for a decade and the foam got rock hard.
Another the thin shell plastic had discolored and degraded from heat and sun. I no longer trusted its structural integrity.

Helmets just are not a buy-one-lasts-forever purchase.

Neither the helmet's thin plastic shell nor the foam are very safe by themself, but when combined and intact they are very strong and provide great protection. Google about the beaks on toucans for an interesting discussion of similar "engineering".

I have a few extra helmets which also lets me color-coordinate with my attire.
One is just for night riding and has my night lights permanently mounted.
Another is for hot weather riding and is more expensive but with better ventilation.