First, it doesn't have to be elevated the entire way, just at surface crossing with roadways etc.
Second, the purpose is not just pure passenger capacity. Sure from a single point to a single point, it makes little sence.
Multipoint to multipoint, get in and pick your destination, it is FAR superior to any other mode of transportation out there.
As far as capacity, this can easily be addressed with multiple lanes of guideway, but really as they are all computer controlled, the spacing can be much tighter.
It's similar to the concept of Google. Instead of one giant super computer processing all the requests, its millions of smaller computers working together to accomplish a task.
There would obviously need to be quite a few PRT cars, but the overall experience would be far superior than what is there today, and could in theory connect all resorts together and to all the parks.