Which of the following is NOT true about online marketplaces?

In many ways, online marketplaces are the perfect business model. Since they facilitate transactions between independent suppliers and customers rather than take possession of and responsibility for the products or services in question, they have inherently low cost structures and fat gross margins. They are highly defensible once established, owing to network effects.

Your lung capacity in late-middle age is in steady decline, as are the fast-twitch muscle fibers that provide power and speed. Your heart capacity has been ebbing for decades. Your sight has been getting worse, your other senses, too, and this, along with a gradually receding ability to integrate information you are absorbing and to then issue motor commands, means your balance is not what it used to be. Your prefrontal cortex — where the concentrating and deciding gets done — has been shrinking for some time, perhaps since you graduated from college.