Some time ago, I got involved in a debate about the cost of unmanned aerial vehicles, UAVs. I argued that the idea that they would supplant piloted aircraft was overambitious, and that, crucially, the high accident rate they experienced would make them rather more expensive than anyone thought. After all, if their biggest advantage was that being unmanned they were expendable, they would be expended - else, what is the point? And expending them means replacing them, and specifically keeping a large stockpile.
According to Wired, 40 per cent of the USAF Predator fleet has been lost since 2003. That is, 53 aircraft out of 139, at $4.5 million each, or $238 million worth.