I doubt the guys filming the crash were part of whatever scam it might be. Their reactions (and their foolish, foolish assumptions that it was a Lambo) seem to indicate as such.
However, I cannot help but be suspicious about the other parts. He repairs expensive cars, and he, almost for no reason, drives it straight into the water. Personally, I think he bought it to fix it and ran into problems when repairing it and couldn't sell it for profit, so he decided to make money via the insurance route...