It's recommended that by age 50 years old you should get your first colonoscopy and then continue with colonoscopies until age 75 years old.
However you can get a colonoscopy earlier than 50 and even later than 75 years old.
Some people stop having colonoscopies after age 75 while some men continue to have a colonoscopy until the age of 85 to 90 years old.
If you haven't gotten colon cancer by 80 or 90 years old then it's unlikely that you will get colon cancer after that.
Most people die soon anyway of natural causes after 90 years old and not everyone lives to be 90 years old and beyond.
My Grandpa stopped having his colonoscopy at age 75 and he never had any colon cancer.