You can set billing alerts that will project your monthly budget every hour, and send you an alert when it's projected to be exceeded.
IMHO your claim (that there is an entry cost barrier) is the opposite of reality. AWS and Google have brought incredible power and choice to developers starting at zero initial cost.
The fundamental issue with setting a limit is it's technically infeasible to decide what to do when it's exceeded. They have no way of knowing what assets to terminate. The way to avoid what you describe is to shut off access to APIs that you don't want to use, and keep your credentials safe.
Then again, I know enough about AWS and how to control my cost.
I mean, yes? You can either build your own for “free”, or pay for the value-add features DO provides that you have described. I don’t see where the problem is.
There is no billing protection (which could make you very poor very fast) and every service has a certain cost and quality which is just not feasable in the beginning.
Even GKE with its free kubernetes master does block a lot of resources on the nodes: https://cloud.google.com/kubernetes-engine/docs/concepts/clu...
Also a ton of great features on gke you will probably never use if you are too small. It is so much cheaper to just get cheap hardware somewhere and put your own k8s onto it if you have more time then money.
Even on Digital Ocean you have the load balancer problem: you need to use the provided and also 'costly' LoadBalancer service. There is only one hacky way to prevent it by exposing your ingress on the host and mapping that one ip but then you loose all the self healing stuff and loadbalancing capability.