You stay in business if you believe that your business model will generate a profit or even just break even and pay all your bills. The AP believes that.
Another analogy for you. You play poker. You're at a table with full of weak players. You're a favorite to win, right? There is no guarantee but you should be able to generate a profit at the table. Now, don't use the word "always". The proper thinking is that over time you will come out ahead at the poker table. Just like over time an AP will come out ahead at VP. Therefore it makes sense to stay in business and continue to play.
Another analogy for you. You play poker. You're at a table with full of weak players. You're a favorite to win, right? There is no guarantee but you should be able to generate a profit at the table. Now, don't use the word "always". The proper thinking is that over time you will come out ahead at the poker table. Just like over time an AP will come out ahead at VP. Therefore it makes sense to stay in business and continue to play.