The market for actual systematic non real-time data on flights etc is pretty diverse (airlines/airports, finance & leasing, maintenance companies and aftermarket parts suppliers, insurance, consultancies), but companies are paying the likes of Corium or OAG for systematic structured data in formats that make creating forecasts or spotting opportunities easy, not because darknet data dumps are the only way to find stuff out about a company.

I'm not seeing much value in loads of Boeing-specific tech data for current generation civil aircraft though. Most of it isn't that secret, there's no viable market for copying Boeing parts without Boeing approvals stamped all over them, maintenance on Boeing aircraft is done at manufacturer-specified intervals regardless of whether it's a Boeing facility or a third party with Boeing approvals, competing aircraft have completely different needs, and if they really wanted to know how Boeing solved a problem that's bugging them they could just poach engineers...