@Cisco1456 What do you mean, what is the money for? The platform requires money in order to function, as every business does. Service fees are used to run the platform.
Service fees are charged on all bookings. There are two fee structures- the split fee option means hosts pay 3% and guests pay anywhere from about 14.5% to 20% (how Airbnb determines that percentage is not something anyone really knows exactly but them).
The "simplified" fee structure means the host pays all the service fees, about 15%. So the guest doesn't see a separate service fee charged to them.
But if the host is paying all the fees, the host would have to increase their nightly rate to cover the increased service fee they are paying.
So in the end, the guest is actually paying more or less the same amount in total- it's just a psychological marketing ploy, like stores putting on a price tag of $14.99 instead of $15. It's only a penny difference, but marketers have determined that the $14 mentallly registers instead of that it's actually $15.