The following piece from lifehappens.org is a reminder of a little understood reality, which is a non-permanent disability is more common than most people realize. Your ability to earn a living is the beginning of any financial plan, which means the ability to earn income is your most valuable asset.
Ask yourself how will you pay your rent/mortgage, car loan, student loan and any other normal expenses if you are unable to earn a living? Purchasing disability insurance assures you will have some income if you suffer a disabling injury or illness.
Which is more likely to happen? Winning the lottery or suffering an illness/injury that will keep you out of work.