Regarding "Simpson said he started collecting Luger pistols back when he was in high school and a good one could be acquired for about $45. Today the asking price can be $6,000."
6000 / 45 = 133.33
This is not sustainable. Today's high school student cannot buy guns anymore, and even if they can, not $6000 guns.
I don't want all my guns increase value crazy like this, if only one can do me 6000 (today) x 133 = 800,000 (future), I will be happy. Extremely unlikely though

But my view is a little bit different on these,,, say, even 6000 today drops to 4000 some years later, the lost 2000 was like taking a vacation, spent, not recoverable, but had some fun.
===
But there are some low cost C&R guns do increase in value quickly.