This concept seems to cause quite a bit of confusion. “Why would you want to fail?” “Are you trying to fail?” 

No, we’re not trying to fail. What we’re trying to do is to test our hypotheses about whether the product or service we think we should be building is actually the product or service the customer wants, and we’re trying to test as quickly and as cheaply as possible. The history of software development projects is laced with spectacular failures which is one of the main reasons for the birth of the agile movement in the first place. We know that failure is likely at some point, so we lessen the impact of the failure by minimising the risk. Build a small bit of functionality, test it with users and if it doesn’t work you can scrap it without falling under the spell of the spell of the sunk-cost fallacy. You’ve also learnt from the experience and can use that knowledge to grow and hopefully improve the next iteration. 

We’re human. We’re going to fail. But that’s a good thing. We learn by experience, good and bad. Failing helps us sharpen our tools.