At the very least, this might be a sign that you should change your pricing structure so that future customers don't end up in that same unprofitable category.
You might also just consider it a cost of doing business. I've heard that Backblaze tolerates a certain number of unprofitable customers because it gains overall from having a single flat unlimited-usage plan.
I'd advise seeing it as a learning opportunity, how much of a loss do you make on these users? Are there any ways you can cut costs to compensate?
Other wise, try raising the price for new customers to a point that if the old customers were paying that you'd make a profit. I bet you won't see a drop in revenue
Say you're bringing your pricing structure inline to be fair across the board.
Give them plenty of notice - say 3 months. Give them the opportunity to cancel if need be. Even go as far as to recommend another service they can migrate to.
At the end of the day your company would be more profitable without these users than with them. If you can turn them into a profitable customer - bonus!
That 8% may be your die-hard fans!
Tell us more.