I gotta admit, my wife is very understanding. She lets me buy whatever I want without any worries. As long as the bills are paid, food is on the table and some money is put into saving, she doesn't mind it at all. It's just an investment that you can have fun with. Sure, maybe you can make more money in a 401k or stocks, but you can't have fun with them.
But some of my investments have turned out to surpass my 401k. How many of you bought these DCM $400 Garands? Some are worth 4 to 5 times the cost. There are also many modern firearms that have skyrocketed in value over the last 10 years.
You can do a lot worse investing your money. Firearms is a safe and honest way to save (and hopefully) make some money. Not to mention the only investment you can enjoy and have fun with for years and years and probably get back your money and then some.