This isn't really a
Tomcat question, but I'll try.
AWS, like some other cloud platforms, is based on the concept of overlaying local mods on a master image. You can then make a snapshot image containing these mods.
Yes, you can resize the virtual disk that you're running on (although
you should consider using an alternative daa-only virtual disk), but that doesn't resize the original image. Basically, what effectively happens when a new instance is created is that a new, blank virtual disk is created, the OS image is copied onto it and booted, and any unused space in the virtual disk is just ordinary free space. If you stop the instance, the virtual disk remains. If you terminate the instance, the virtual disk (and its contents) are deleted. Eventually. AWS cleans up when it's convenient, so it doesn't immediately delete terminated instances.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.