Yelp: Very hard to monetize. Because they chose a model where the businesses who pay them are also the businesses being reviewed, they&#x27;ve given themselves a conflict of interest. They&#x27;ve chosen to sell their integrity, which makes their star ratings less reliable&#x2F;valuable, which makes users trust them less, which makes businesses want to advertise less. It&#x27;s a vicious cycle.<p>Zenefits: Broke the law. Also an insanely ambitious, brilliant, risky business model.<p>PayPal: Hated by most people&#x2F;customers. Can&#x27;t wait until they go out of business completely.