The big empirical evidence that those deathbed platitudes are right: The Harvard Adult Development Study. The results are clear: achievements (even for people who achieve incredible, world changing things that most of us could never hope to come close to) aren't strongly correlated with happiness at any age. Good interpersonal relationships, in contrast, are the most powerful happiness determining factor.
Until you realize that some achievements are needed to have good relationships.
Achieving or accomplishing something is important, it's not so important what exactly, but if you never achieve or accomplish anything at all you will have difficulty forming relationships with quality people