While many firearms (including some of mine) are not practical, full autos are pretty much useless IMO unless you have a lot of money to turn into noise. Once the "bad-ass, cool" factor wears off (which was real quick in my case after I paid to feed one), the shine went off quickly. This was with 9mm back when milsurp was way cheap. The guy that owned it sold it due to operating cost.
As for money, $1,200 was a LOT of money in 1968. I graduated from Purdue with an engineering degree in 1973 and started with Deere & CO. at $1,100 a month. That was very good starting money. $1,200 would have been maybe 2 months take home income for the average person.
In constant dollars, I'm not sure that full auto is a whole lot more now than it was then.
I have no problem with someone owning one. I just want something I can afford to actually shoot.