Life can't be the "greatest good," otherwise, death would conversely be the "greatest bad." And death is nothing to us.
Pleasure (i.e., living a pleasurable life) is the goal, telos, beginning, and end.
When I read this in DeWitt, I took it not as an adjective (whose opposite would rightly be "bad") but rather as noun; as in the best thing we could ever have; and if we lost it, we would be loosing the greatest thing we had. This doesn't imply that we should fear losing it, as long as we're certain we are giving it and will keep on giving it the best possible use towards the ultimate goal of pleasure, the thing that is most greatly good.
Was I interpreting this wrong?