hardcap only shows that investors believed in that particular project. but this trust doesn't guarantee that developers will succeed in the future.
ICO project can turn into a scam although reaching hardcap. Meanwhile, some other projects may fail in the next process which causes the project to not be able to reach the exchange and eventually have to refund their investors. Indeed, hardcap is a good sign for the future of a project, but it doesn't always end with a good story.