A nickel is worth 6 cents of nickel, if it was pure nickel
You don't have your facts straight, the spot value of 5 grams of pure nickel would be more like 10.6 cents at current prices. The 75% copper component actually makes up more of the metal value of a US nickel than the Ni component does currently.
The cost of extracting the nickel from a nickel what with all the impurities is going to make the effective worth of a nickel more like 4 cents anyway, and you'd be lucky to get 2 cents or so from a scrap dealer, since scrap dealers also want to make a profit too.
You're assuming that the component metals would need to be separated, but cupronickel alloys are good for more than just coins, particularly for corrosion resistance in marine applications. The coins don't have to be melted to use them as a store of value either. I still don't really save US nickels myself, because I'd rather sort for coins that already trade over face value.