You are talking about a chromosome that is identified in an entire population and trying to figure out the cause or origin of that chromosome. Fusion is simply a proposed hypothesis. The chance of that event happing by the hypothesized cause is very relevant to the strength of the hypothesis.
The poker analogy was a response to @CrisprCAS9 who used this analogy. One event that has odds of 1billion to one is equivalent to 3 consecutive events with odds 1000 to one. Statistically 3 consecutive events can be equivalent to one single event.