We are always afraid of losing something. Some are afraid of losing trust, some are afraid of losing a job.... A race, a friend, money, a place to live in — all of that could be lost. However there are times when you are afraid of losing something you didn't have. Sounds quite strange, right? Let me give you some examples.
Lose — be deprived of or cease to have or retain (something).
Imagine you are a freelancer or an agency owner — clients hire you to get some expert job done. When getting on a call with them, you might not want to lose this client, if they have have a good project or lots of money. But the problem is, they didn't hire you yet, so you can't lose them. It's not a race, it's a matter of helping each other or exchanging value. And if you don't lose them on that call, you may get in trouble later.
Now imagine you are launching a startup. You have some users of your product, a lot of leads are coming to your landing page. However, not many of them are buying your product. What is the problem? Maybe it's your product, maybe it's your website, or maybe you are just driving the wrong people to your website? I believe in many cases it's the product, but you may think it's the website. So you try to increase the conversion by changing the website. This is how dark patterns are being born on the web. All those popups, screaming headlines and misguidance is usually the despairing attempt to sell a not so great product. And that's how you lose trust, not only “your customers”.