its expensive if you misuse it, those cloud providers provides services and computing models that cannot be found on low cost providers such Serverless and Containers.
Basically, AWS (or any cloud provider) is great for young startup with 0 money, medium sized companies who can optimize to some degree and big sized companies too big to organize efficiently the logistic of buying servers and the instrumentation of infrastructure. It leaves the mid sized startups which have an interest of buying their own infra, but migrating away from a cloud provider also have a cost of itself.
It's not as clear cut as I am stating, you also have cheaper alternatives than AWS, Azure and GCE. You can go for OVH or DigitalOcean, less possibilities and technical offering, but cheaper prices which can compute with hosting things yourself mid-term.