Tl;dr: "Sell your customers what they want, make them pay what you say, be sure they're rich enough."
Best paradigm busting advice in business after "If you can secure just 0.1% of the chinese market, you'll have 5 milion customers" and "Always remember: profit is revenue minus expense".
If school is currently teaching this, it is seriously failing its mandate. This does not mean that using sort(3) as a solution to a sort assignment should be acceptable.