To the last two questions: no and no.
No one can buy the Fediverse or Mastodon because there is no single thing that could be bought. The Fedi is made up of thousands of independently owned and run servers, which makes it extremely difficult or impossible for anyone to buy the network.
Most Fedi servers belong to unpaid volunteers, or non-profit community groups and co-ops. The running costs are covered by the server owners themselves and donations from their users. There are no investors, no venture capital firms, no ads, no trackers.
Companies can start their own Fedi server if they want to, anyone can, but all they would control is their own server. They would have no control over the thousands of other servers out there.
The Fediverse is built on free and open source software, made by many independent groups, and the software copyrights are licensed in such a way that no company or organisation could ever take control of them.