Took me a few reads too. I think the intended meaning is: "There are those who are convinced that there is more to things; they spend their time chasing that '

Took me a few reads too. I think the intended meaning is: "There are those who are convinced that there is more to things; they spend their time chasing that 'more' but typically don't find it. And there are those who are convinced there isn't more to things; they find themselves frustrated at the abyss."