your argument seems less convincing also.

What a weird thing!

The convincingness of an idea can depend very much on one's mood. This is obvious in cases of clinical depression, but I think it is present in ordinary mental functioning as well. We tend to judge convincingness by narrative coherence rather than logic and evidence. The coherence is not just the coherence internal to the story, but its coherence with one's own feelings and experiences. As the latter change, so does the convincingness of the story.

Hypothesis: Ideas that retain their convincingness in the long term do so not by being especially rigorously argued or supported by solid evidence, but by constituting a large enough, coherent enough story to crowd out influence from day to day experience. It is the experience that will be interpreted in the light of the story rather than the other way round.