Why does faith in wonder fade with age, leaving only cynicism?

Because you confused faith in wonder with faith in magic — a God who is your waiter. What faded was not faith but a childish picture of it, and its loss is a grief worth naming, not a proof of nothing. Ask to see the wonder that does not require the laws of nature to break: breath, the turning morning, a person who chooses to be kind. Cynicism is armor against disappointment; ask, slowly, for permission to set it down.

The tradition speaks of hitchadshut — renewal: it holds that creation is remade each morning, so that even a tired soul is offered a genuinely new day.

From the sources “Those who sow in tears shall reap with shouts of joy.” — Psalm 126