[0]: https://www.navycs.com/charts/2019-military-pay-chart.html
The other thing that can confuse this issue is that Generals and Admirals generally (sorry) keep their titles after retirement. So if you have "Gen. James McClinton" on your board, that doesn't speak to whether or not they're active.
From looking around, it looks like board recruitment efforts toward Admirals and Generals are targeted at those who are retired or nearing retirement: http://blogs.reuters.com/financial-regulatory-forum/2012/01/...
https://ogc.osd.mil/defense_ethics/resource_library/deskbook...
seems like a general with a 40 year career who could (and did) save all of his money could have accumulated a few million dollars in cars without very many shenanigans, if that was their sole financial goal in life.
I kind of got the impression that the military isn't seen in that way in the USA and didn't have such a high social status
By no means are officers all from wealthy families, but those folks are definitely over represented.
Of academy, ROTC, OCS, and direct appointment, I'm relatively certain that, unless things have shifted recently, the academies are the least significant source of commissioned officers in the US military overall, rather than the second major entry point.
Or have, or at least have once had, a lucrative side business (military personnel can do this, legally.)
Or have inherited money.
Or have a spouse with a greater income or inheritance.
Or restore cars, such that the market value of their vehicles vastly exceeds the purchase price.
Or purchase cars that have significantly appreciated in value for other reasons (lots of high-end luxury cars that are limited run not only are pricey but limit sales to selected buyers, and the market value of the cars is almost immediately much higher than the purchase price and appreciates rapidly.)
Or a combination of the above.
Of course, it's also possible the general saved up, or made lucky investments, or married into money, or there was an exaggeration or misunderstanding.