A real world example in speculation and calculated risk:
In my last career, I was a self-taught, self-employed numismatist specializing in rare die varieties of Morgan & Peace silver dollars.
So I'm at a coin show and I was reviewing auction lots that day when I came across an 1878 Morgan that I attributed as an obscenely rare VAM 123. Not only was the variety rare, but it was certified by NGC as MS64 DMPL. The only other known example of the variety was an AU53 (almost uncirculated), and was firmly placed in a collection.
At that time, a typical 1878 Morgan Silver Dollar graded NGC MS64DMPL traded at about $275. I, and I alone, estimated the value of this coin at $10,000-$15,000. I stood to make a tremendous amount of money…. If I was right. If I was wrong, I lost nothing because I would have paid $275 for a $275 coin…. Or so I thought.
The auction begins. When the bidding on the coin exceeded $500, I confirmed my fear that at least ONE other numismatist also attributed this coin as a VAM 123 variety. As it turns out, it was just one other person.
This is where I entered the pure "SPECULATION" aspect of this purchase. Remember, I was the only person on the planet who estimated that I could sell this coin, wait for it..... in the future, at $10-$15,000. I could have been completely delusional as there was no precedent. And without at least one other person in the world agreeing to MY value of this variety, its real world value remains at $275.
The bidding on this $275 coin gets to about $6,500 when the other bidder bows out. With the juice, I owned this normally $275 coin, at $7,500. Fuck!!!!
As expected, my attribution of the variety was completely correct. A couple of weeks later, I won my house in an auction. Then in an effort to quickly gather capital for the purchase, I immediately sold the coin to my best client for $10,000 without even shopping it around.