Well, it's not quite that bad. Get one or more wrong and you might not maximize your profit, you won't necessarily lose money.
I'm pretty sure the key to making money on anything is simply "buy at the right price, then sell at the right price". But if you choose the wrong time, you won't get the right price, and if you choose the wrong coin, there might never be a right time.
The list is long and disputed, so bottom line is choose the ones you think have potential. Just one example that we disagree on is the 5oz "Pucks". I've seen you dis them as over priced bullion, yet ignore the crazy low mintages. These Pucks are in the Red Book, so future generations will recognize them as US Coins. Will they desire them, who knows. The US Mint is flooding the market with too many different rare coins, many more rare than surviving examples of classic rarities, some will be winners, some will be losers.