Sorry you couldn't get to see your grandkids over the Christmas.
However you're leaving out too much detail for anyone to assess your situation and I've never heard anyone who got bumped 10 times in a row. If that was the case, Delta is obligated to get you point A to B even if it means they have to buy you a ticket from another airline. So you're leaving out a lot of facts or no one here will believe your story.
If they indeed were bumped 10 times as you mentioned, they would have been offered a minimum of $400 in compensation per bump. That should yield $4,000 per person. Hate to miss Christmas at home but sign me up any time for a chance of getting 10 bumps in a row.