I don’t think the “original six” are immune to losing . Toronto lost their sellout streak a couple years before Matthews was drafted. Chicago couldn’t draw flies during the last years of “Dollar Bill” Wirtz’s ownership. Even Detroit while winning had plenty of tickets available during the last Stanley Cup runs.
The other points are about the NHL being a business. The percentage of hockey fans is only part of the big picture and apparently not enough to make the business viable. That means they want corporate support and the high prices they can pay and a population high enough to have people pay season ticket prices . If the population doesn’t want to pay, it isn’t an NHL hockey market.
After all star players are rightfully well paid, the cost to run a winning franchise is high. Also the value of the Canadian dollar plays a huge roll in the viability of markets up north. The pay is in US dollars (or indexed to) even in Canada.
For those who don’t want to pay NHL prices, there’s juniors, the AHL, the ECHL, college and high school. I’m lucky I live in an area near all those. There is also free. Hockey players practice and scrimmage in the summers.
Right — those old teams aren’t immune to losing, but you really have to run a dysfunctional franchise for years before your fan support starts to erode. Detroit is probably a function of a different factor: the team was so good for so long that anything short of a trip to the Stanley Cup Finals was seen as a failure. The New Jersey Devils faced a similar problem in New Jersey after the early 2000s, too.