There are many ways your Mac can get damaged, become outdated, or otherwise experience greater wear and tear from use that can shorten its lifespan. Regardless of whether you purchase it new, refurbished, or used, your Mac is likely a sizable investment that you might wish to keep running for as long as possible, not only because of the cost factor but also because of the time and effort it would take to migrate your data and workflow to a new system (even though Apple has made the latter quite easy if you have proper backups).
