Before we dive in deeper, let's just say it's completely doable 🙂
To achieve this, you should run Tickera in WordPress multisite network. If you are not quite sure what it is, please read our post about it here.
This will allow you to dedicate a subsite to each of the event organizers where they can create and manage only their events and tickets and use their own merchant credentials to collect funds from the ticket sales. At the same time, you, as a network admin, can take a cut of each of the tickets sold in your network by utilizing PayPal Chained Payments and/or Stripe Connect.
However, bear in mind that Tickera events and tickets cannot be created and managed on the front end so event organizers would need to use WP admin area of their subsites to do this.