"but Twitter is fat and everyone knows it"
Everyone knows it because it's what everyone on the right has been stating without evidence for weeks. You've heard it so much it's become like an obvious fact even though you can't point to any hard evidence. I say this because you make statements like that. As if you are saying "The capital of France is Paris".
You also said
"Twitter does not include 7500 employees, unless ~6000 of them are working on something other than Twitter."
How do you know how many employees it takes? How do you know 1500 is all they need? You just keep making statements without any backing them up nor do I think you can unless you're C level at Twitter
Also any company might be losing money with staff being the main reason but still need that level of staff.
Has hundreds of millions of users and had an awful lot of advertiser accounts. How many accounts does SpaceX have? Yes, a lot more now that they've got their Internet service, but managing users is labor intensive, even if you don't provide many means of contact. Advertisers, especially large brand accounts, is labor intensive too, and if you lose half your big accounts because you cut staff willy-nilly, there goes a lot of revenue.