What do you mean your username?

No different than email. That's why domains should be displayed in clients for users.

This "problem" isn't new or unique to the Fediverse, or even to the Internet. It's much much older. What's to prevent someone from hijacking your name?

Most societies converged to a simple solution: surnames. The Fediverse is not different. "YourHuckleberry" is your username and "@lemmy.world" your usersurname. It is impossible to hijack your name+surname.

It's always been so. John@aol.com, john@outlook.com, john@foobar.com, ... What's the problem?

None. Lmao. This is by design.

Welcome to freedom!

Nothing, really. Each instance is unique. Technically speaking, users will the same name on different instances are unique. You can always spin up your own instance and get whatever name you want. So it's natural to want to register a username in multiple instances, to avoid confusion. Eventually there will have to be some way to tie identities across instances. Like a GPG key that can be validated on all accounts belonging to the same person.

I think this is ultimately where Meta is going with their Fediverse stuff. They will operate as a low-key ID verification service. Instances are saying they won't federate with Threads right now, but as shitty as Meta and Instagram are they can guarantee that a Threads user is the same entity as an Intstagram user, which is currently more ID verification than exists right now in the Fediverse. Some instances may open themselves up to Threads in order to gain access to their userbase.

Nothing at all

I'm Your Huckleberry

Nothing, but keep in mind that maybe 95% or even 99% of the fediverse users are a bunch of nobodies. To have a stalker or someone trying to impersonate you, you would have to be extremely lucky (or unlucky)

I'm sure this will happen. People do get crazy when Internet arguments occur. But what is the risk to you I wonder? If they do something that will get them banned, it will only affect that account. Do others really pay attention to usernames? I don't.. I could see someone coming into a contentious debate and trolling but ultimately do any of these debates really matter outside of just the sharing of knowledge and ideas? I'm trying to think how it could really negatively affect me other than just being rude and offensive to my ego.

As others have said, nothing.

Mastodon has a sort of lightweight verification which just signifies that you are to some degree in control of the URLs linked to in your profile. So for example, if you have your own domain or something that people associate with you, then you can use that in your profile to show that it's you. Of course, that depends on that domain meaning something to the end user, and the end user being savvy enough to, for example, know that someone could get the .com version of your .net domain, etc. etc.

Same thing as email addresses

I'm sure this will happen. People do get crazy when Internet arguments occur. But what is the risk to you I wonder? If they do something that will get them banned, it will only affect that account. Do others really pay attention to usernames? I don't.. I could see someone coming into a contentious debate and trolling but ultimately do any of these debates really matter outside of just the sharing of knowledge and ideas? I'm trying to think how it could really negatively affect me other than just being rude and offensive to my ego.