>>81797250It also makes more sense in-universe. He realizes he can't be "so incandescent" but instead of growing as a person he becomes consumed by his obsession with the sun. It ties back into his character being a soft critique of evangelicalism while also providing a bit of tasteful cynicism.
And let's be honest, Solaire is weird from the moment you meet him, to that homoerotic comment he makes, to the obvious Don Quixote inspired outfit.