Thus, the sustaining & enhancement of one's life and of those whom they value is as much an objective good as you could ever hope to find, IMO.
The problem is that you do have a hope to find an objective good. Why is that?
Ummm... same reason I seek objective truth? Because we live in a world that is really there, the principles & laws by which its operation is governed are objectively true or false? The alternative would be solipsism, and IMO solipsism has not done anything for me lately. (But maybe some solipsist will pipe up and say, "it works fine for me!") <ahem>