The biggest mistake I see is that people jump into AWS whole hog without doing the research or if they are large enough, hiring someone who knows what they are doing.
https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2...
Just like AWS is not understandable to someone new, I feel the modern front end ecosystem is royal cluster but yet and still thousands of people understand it after a 12 week boot camp.
It's not my intention to victim-blame here, yet do bear in mind that there are many, many ways to use the services and to expose resources to the bottomless appetite of the internet. Maybe Digital Ocean or Linode or the like would be a better option for starting out.
EDIT: sorry, I forgot to include the screenshot link - https://imgur.com/a/tVFoocr
https://aws.amazon.com/premiumsupport/knowledge-center/s3-fi...
Why do people think that they can give Amazon a credit card number and expect everything to be easy enough for them and suitable for a large enterprise? AWS offers something for beginners - Lightsail. When that outgrows their needs, they can peer their behind the scenes LightSail VPC to a full fledge VPC.
It could be there are such tools. But they are impossible to find, setup or understand for someone who is not already an AWS expert. I recently got a $500 bill from AWS. It was impossible for me to find out which S3 buckets (or even specific files) caused these costs. I looked at this for half an hour and have used AWS before. They just don't tell you how to obtain this information. Or maybe they do, and it is so well hidden that it might as well not exist. This was a horrible user experience. As a customer, I want to know what I'm being charged for. The fact that AWS make it so difficult make me never want to use them again.