The problem is that real world sunk-cost fallacies are never that cut and dried.

Such as the submarine-yacht. Now that a competitor has come out with one, you are in a good position to reap the rewards of their advertising campaign.
It takes a lot of advertising to introduce a completely new product.

And, although you are 9 mill down, you also have a design / research group already set up to take advantage of reverse engineering and learning from your competitors.

But, reality usually is something more like a bird in the hand is worth two in the bush.

Do you forego your current plans, the one you are good percentage done, to go for a better plan? Its a hard choice

The stock market (crypto markets) provides the best examples sunk cost.

So many are like, i spent $10,000 on bitcoin, and now it is worth only $8,000, i will sell this crap as soon as it goes back to $10,000