It actually works out cheaper in most cases to use the playground over actually paying for chat gpt plus

True, but these are problems which have been solved. You use a cache in-front of the database and then use replicated instances of the databases with sharding and then use load balancing and connection pooling etc

I don't understand why a dedicated server is a good idea, when the only true way to scale is to use like Kubernetes or Docker and ECS Containers with scale?

Your just gonna run into more problems, you cannot vertically scale forever.