Cost of the software, the computers, the video editing platform, the cameras, mics, lights, etc., etc. It'd be easy to blow over $5k alone on camera gear, never mind the computer or the software.
I remember when I first got 3DS Max. Had been saving for years (buying that program was going to be like setting off a nuke on my bank account) and the boss surprised me with an old version as a gift. Such powerful software.