You're assuming that a physical desktop or laptop is the alternative. Likely this is an alternative for people using vmware horizon or citrix for virtual desktops. In which case you'll be spending almost half that on just the software, not including any hardware at all.

I'd need more info on the service, but I'd imagine this is very cost competitive. As to "why?" - because for things like HIPPA data, I'd MUCH rather have my doctors/IT staff logging into a remote desktop session that I can lock down so if their laptop gets stolen from their car I don't have to worry about whether or not some day someone will be able to crack drive level encryption. Or worry that an employee didn't have drive level encryption for some reason. Same for financial institutions/etc.

Furthermore a doctor or insert staff can connect from home, and I don't have to worry about whether or not they properly secured their home desktop. Yes there is still some attack surface there, but far, far less than them storing files locally on their home PC.