The trick in conversion is that you want to pull people into your service, rather than pushing your service onto them.

To use a sales analogy, imagine you're shopping for a car. You visit a salesman who's very pushy. They tell you all the reasons you need to buy this car, insist that this is the best car for you, and put you in the car. Then you drive the car and realize it doesn't meet your needs. You might think the salesman was terrible and vow never to visit them again.

Conversely, imagine you meet a very different salesman. They let you walk around the lot, answer questions about each car, and maybe even talk you out of extra features you don't need. "Yeah, the SUV will have more room for groceries, but for your daily commute the fuel economy is going to bite you." You'll probably respect that the salesman is trying to meet your needs, and the next time you're shopping for a car you'll visit them again.

Getting people onto the fediverse is somewhat similar. We're already here, and if you've been here for a long time then there's probably a bunch of things you like about it. You might insist that your friends should join lemmy because it's open-source, ad-free, aligns with your politics, decentralized, or whatever. But if you're leading with all that, then you're putting your values onto the person you want to join. If those values don't align, then maybe they'll join, but they'll just as quickly leave if it doesn't immediately mesh.

When I want to pull someone in, I'll mention that I saw some meme / post / video or whatever on lemmy, and then tell them about the post. You're leading with the value of the content, and if the person you want to join also enjoys that content, they might ask what lemmy is. This is your invitation to pull them in.

Okay, so you asked for a one-liner, and here it is: "It's like reddit, but it's free from ads and corporate ownership."

If they seem interested, give them a link to whatever instance you're on. A lot of the time we might want to talk about the whole decentralized thing and picking out instances, but if you know nothing about the fediverse then the process sounds confusing and can turn people off. Just a link to a registration page will do and they can take it from there.