In the end, assuming anyone bids at all and all the bidders are rational, someone will make a profit. It just won't be a very big profit, probably.
My guess here is that bitcoin is considered property and not currency, and there are laws around this.
Edit: Looks like they are treating bitcoin as property -https://www.usmarshals.gov/foia/directives/asset_forfeiture....
FinCen is not limited in congressional currency designations to carry out its regulations. Only services that exchange national currency to bitcoin are regulated under FinCen. Bitcoin is not regulated by FinCen.
Also interesting to note that in previous auctions it looks like USMS only conveyed a "bill of sale" for the bitcoins. We don't know what arrangements were made for conveying the bitcoins themselves. I would speculate that they were transferred to a wallet designated by the buyer, but it's possible they were not.
That is, whatever happens in the future between Bitcoins and the Gov/Fed/Treasury, your lot might have a standing in a court of law that other lots might not.
This sale basically cleans these coins from all previous illegitimate and/or illegal transactions that they went through - whether some of these where stolen, used to buy drugs, not reported or accounted for correctly with the IRS, etc.
In a way you are getting a government issued certificate of legitimacy. And you will not have to prove anything - when others will have to prove how they acquired theirs.
Their last auction was 44,000 bitcoin worth $20 million