This may just be the masterpiece of Don Rosa's work, that's for sure. One element I liked was that it pretty much stated outright that Scrooge's Number One Dime wasn't a good luck charm, and that it didn't bring him any good fortune during his formative years. What it DID do was INSPIRE Scrooge to win his fortune, and reminded him constantly of his vow to Get Rich, and Do it Square.
Which, interestingly, also explains why Magica DeSpell is so obsessed with getting it for herself. She ~knows~ the coin wasn't magic when Scrooge got it. But he's kept it with him throughout the years as he earned his fortune. And thus, over time, "charged" it with symbolic energies of wealth and good fortune, thus giving the coin a lot of mystical potential for the likes of Magica.
By the way, I know a website where full scans of the whole mini-series can be found, but I don't know if posting the link would violate this community's rules.