I think you underestimate how strong the masts of a sailing ship are. They are the main propulsion of the ship, they have to take the entire wind load (or in the case of a three-masted ship, depending on sail plan the mainmast might normally take about half the total wind load) and it takes a very significant wind load to haul a ship like that through the water at a dozen knots. The mast is a main structural member and is typically tied into the ship all the way down to the keel, as well as being heavily tensioned in every direction practically possible with rope stays. Granted this is done especially from the rear and sides more than the front, where they would not typically be expected to experience significant direct loads like an impact, but this is still a serious piece of heavily reinforced structure we’re talking about despite its thin appearance.

Also I can’t tell if they’re wood masts in this case, but if they are, those tend to explode into potentially deadly splinters when they’re broken like that. Sailing injuries used to be pretty horrific and dangerous.