Does everyone have degenerative disk disease?

Somewhat: Degenerative disc disease is wear and tear on the bones and discs...Sorta like arthitis. Just as anyone who walks will eventually have some degeneration of the knees...Anyone who walks upright will eventually get some degeneration of the spine. Actually the treatment is often the same as well - strengthening the muscles around the affected joints and maintaining flexibility.

30%Very impt concept: 30%of asymptpmatic volunteers over the age of 30 have evidence of disc degeneration on MRI this increaes with age in other words if you guess or assume a MRI abnormality is the cause of you back pain your wrong 30%of the time not a very good test for pain inaccurate at finding pain scources in back shows a lot of asymptomatic disease that requires no treatment.

Probably: Degenerative disk disease is a radiologic term. Most people over thirty have imaging bone changes that warrent this description. Notably, most of those with these changes are asymptomatic. Unfortunately, doctors conscript this term as a "diagnosis" when they are stumped for a diagnosis; at least this has been my own experience.