Thank you for the responses. I should probably clarify my post a bit.
Some of my early exposure to firearms was through a junior smallbore rifle club back in the 1980's. After being involved with the club for several years, we found out that one of the guys who ran the club was probably one of the largest machine gun dealers in the country. He had roughly 400 machine guns in his collection at the time. That gentleman is long since deceased; however, participation in that club sparked my interest in firearms.
The question is really about do you see machine guns differently from regular firearms? Do you consider them to be objects of desire or are they additionally tangible assets which can also be enjoyed?
For example, I consider most of my regular firearms to be a hobby. I buy guns because I find them to be extremely interesting. I actually get to shoot them far less often than I wish. At the end of the day though, they are basically toys. I don't have an expectation when I buy one that I will ever get my money back.
For me, a machine gun is different. Yes, they have all the appeal of a regular firearm (and more); however, I would not be able to justify one (at the price premium over regular firearms they demand) for myself if I didn't see them as scarce assets that will likely appreciate in value over time.
Yes, I absolutely wish machine guns were no different than any other firearm. I would gladly see the Hughes ammendment repealed and their value drop. Being pragmatic, compared to other non-tangible or tangible asset classes, I see full autos as having at least as much upside as most other asset classes. All asset classes have risk. I have lost money in the stock market (and I cannot enjoy a brokerage account directly). Precious metals, cars, etc. all have their own risks, and frankly, I don't have nearly the personal interest in any other tangible asset class.
Let me ask the question this way, would you buy a machine gun if you knew for certain that five years from now it would be worth less than half what you paid for it? My wife compares a full auto to a new sports car. In that light, I consider a new sports car to be a toy while a machine gun is an enjoyable tangible asset.