Ability to teach isn't just useful to teachers. Being able to understand an idea well enough to convey it to others will help you internalize it yourself. Not only that, but it will make you more effective at being both a leader and a team player:

We’ll tell guys up front, “Hey, your primary job is as a teacher, as an instructor.” Our bread and butter mission is unconventional warfare. The Surgical Strike portion of our portfolio is important no doubt, but the Special Warfare part of that portfolio is what people need to understand. It implies that we’re going to be working through proxies. That means I have to be able to teach. I need to be able to convey information. I need to be able to influence diplomatically, because these are partners. They’re not subordinates where I say, “You do this.” You’ve got to win them over. You’ve got to be able to convince them, so if you can’t instruct, if you can’t work through a proxy, through another party, and you’ve got to do everything unilaterally yourself, as an SF guy I don’t want to say you’re worthless, but you’re not that valuable.