They get a regular salary they sign of in contract.
Fiverr is an advertisement site and money/service transaction site with additional money/client protection feature.
Signing up to display your ad on the site doesn’t make you part of Fiverr company in any way shape or form.
"Furthermore, Fiverr is not responsible for the content, quality or the level of service provided by the Sellers (even if they are Pro Sellers, Top Rated Sellers, offer Promoted Gigs or otherwise). We provide no warranty with respect to the Gigs, their delivery, any communications between Buyers and Sellers, and the Logo Designs created through the Logo Maker. We encourage users to take advantage of our rating system, our community and common sense in choosing appropriate services.
By offering a service, the Seller undertakes that he/she has sufficient permissions, rights and/or licenses to provide, sell or resell the service that is offered on Fiverr. "
Sellers chose to put price on their service high or low.
And 70% of them have no skill what so ever regarding the service they claim to be able to provide.
Developers are Fiverr’s employee. Users are not.