A Reason (n.) need not precede a choice; why should every step be preceded by another step?
A Reason (n.) is not a cause: an observer may learn why the tribe bets as it does while the bettors themselves used no reasons at all.
A Reason (n.) is a way that leads to an action: sometimes the road one actually walked, sometimes a post-hoc justification that merely fits accepted rules.
Reason (n.) runs out, and then the question 'why?' still gets asked — and we answer with a cause instead.
Reason (n.) go on too long when one misunderstands what giving a reason is for: a profound point, hard to state unambiguously.
A Reason (n.) eventually runs out: he must go on like this, not because he cannot yet grasp why, but because in this system there is no why.
A Reason (n.) can be given only within a game; the chain of reasons ends at its boundary.