Get your miles to gift cards (paths vary) and then convert those to cash.

example:
higher status DL members can convert directly to gift cards at 1 mile= 1 cent. Sell thse to Plastic Jungle/Ebay/etc and your 10 million miles become $70,000+.

Horrible redemption value, I also think someone with that point wealth would have a corresponding net worth to not need to resort to such measures. Then again my pile of points has never topped 250k before redemption so relatively I am a potato sack peasant.