The conclusion does not necessarily mean that the premise is wrong, meaning it's okay to trust in ourselves forever, but it does not mean that nothing else matters. It only means that we can use the self as a standard while comparing or contrasting with other things.
I don't think we can trust in ourselves forever. Human beings are weak. Only in believing can we be strong. When I say this I mean believing in God of course. This is my understanding. We know what happened to people who believed and trusted in themselves in Germany during WW2, at least the Hitler's followers. They also thought that nothing else mattered. Where are they now?