Is it possible to impersonate the Discobot?
AI-generated summary
Impersonating the Discobot is only possible for sysadmins, whose email addresses are specified in the app.yml file. JammyDodger and ClawdiaWolf confirmed that only these accounts can impersonate the Discobot. The DISCOURSE_DEVELOPER_EMAILS setting in app.yml must be updated with the desired email addresses, and the app must be rebuilt for changes to take effect. If the “Impersonate” button is still not visible after these steps, users should verify that they have completed the process correctly. Some users have questioned the need to impersonate the Discobot, with not-ethan jokingly suggesting it could be for a party with a disco theme, but suteroun and tobiaseigen are still seeking assistance with their use case.
Yes, if the account is a developer account (from app.yml) - adding this information from @JammyDodger in case this message is marked as solution.
I believe only sysadmins can impersonate Discobot (ie. the accounts of the emails in the app.yml). Same for system, and I think other admins too.
I’m kinda curious to know why anybody would want to impersonate discobot. What’s your use case? 
I tested by creating a new admin account and I indeed can’t impersonate Discobot with this one.
I edited my previous message 
People having a party with a disco ball and want a user that loves discoing (If that’s a word)
I can confirm this. I sometimes need to impersonate other admin accounts (long story…) and had to add my admin account’s email to app.yml before I could do so.
I added my mail address my admin account to containers/app.yml in DISCOURSE_DEVELOPER_EMAILS and the mail of the admin I want to impersonate. But when I open the account in admin settings, there is no “Impersonate” button.
What did I forget?
Did you rebuild the app?
Ok, I had already thought about that. Thanks, then I know now.