My position on shooting full auto is that it's not that expensive, especially when compared to some of the other things people do for shooting sports recreation and non-shooting sports recreation.
First of all, you need the gun first. For that, you're talking easily 10-30X the price of equivalent semi-auto, for each MG. Considering the vast majority of firearms collections are (allegedly) less than ten weapons, the acquisition of the MG itself is a complete non-starter for the vast majority.
Second of all, is the ammunition consumption. It is certainly true that even expensive MGs are capable of shooting many times their value in ammunition, but to do so is --again-- immediately impossible for the vast majority. When many refer to MGs being too expensive to shoot, they are referring to the fact that their desired ammunition consumption would be much higher than for their semi-autos.
So when compared to the cost of other shooting sports, shooting full auto is either roughly the same or not that much more expensive than other shooting sports.
Well, compared to the cost of a transferrable M60* (or two), yeah I can see how you might conclude the operating costs of full/semi autos are similar. There's also the cost of insurance (unless you're an idiot) and maintenance to consider, if you want your 'investment'** to retain its value. There's also the high 'opportunity cost,' represented by how many other firearms would be missed in order to afford the machine gun (this is why I personally do not partake, as one or two MGs would replace a dozen that I also enjoy shooting). Lastly, the investment is becoming increasingly risky, as we approach the logical conclusion of a final ban on MG sales or the dissolution of the Hughes Amendment, and for many it is a lot of money to tie up in a single undiversified investment that can be destroyed in an instant.
I've got no problems with people owning nice things. I myself own a very nice automobile, and many nice firearms. I got a good education, a job, and work hard and save my money to be able to do so. Same as doctors, lawyers, and other professionals who are able to realistically (and responsibly) afford expensive machinegun purchases. Most I've met made no bones about how out of reach these machines are, and lament it (because it limits their ability to partake of even more machine gunnery, and because it necessarily marginalizes MGs' protection in this country)
Pretending that these luxuries are affordable, or can be responsibly purchased by most (or even many) gun owners is something of a sport among a few in the NFA crowd, I've noticed (just as high-fashion snobbery is a sport among some of the general gun crowd). I don't know if it's people trying to rationalize an exorbitant purchase, or the so-called 'humble brag,' but it is more irritating than not to people who are already fully aware of what they can afford. Just be happy and honest you can enjoy the rarified atmosphere of machine gunnery, and recognize that the great majority of your fellow gun owners are unable to share it with you (and work with them to take down these stupid NFA barriers in the future)
TCB
*what, like 60-70 thousand dollars each, these days?
**"investment" is an odd word for profiting from the US govt's unjust restriction of our civil rights