No project, no brand, no company exists in a vacuum. You make bets about external forces when you build something.
If you want to cross the Atlantic by boat, you can build a sailboat. Your bet is that the wind will be right when it's time to sail. Or you can build a motorboat and deal with the noise and expense, but insulate yourself from the wind.
If you launch a $100 million magazine, you're making a bet that the advertising environment will support you a few years down the road. If you spend four years getting an advanced degree in computer engineering, you're making a bet that there will be plenty of high-paying jobs still waiting for you when you graduate.
If I had a hundred million dollars to invest in a business magazine, there's no way I'd invest a hundred million dollars in a business magazine. Why put all your chips on one medium, one source of revenue, one model?
The external factor is not disconnected from your bet. It is your bet, your decision. Damning the gods of fate because you made the wrong bet makes no sense. I rarely see business plans that have a section entitled, "External forces we're depending on." Acknowledging that things out of your control will change is the first step in hedging your bets in advance, just in case.