I mean you kinda gotta take a step back and look at the people that start them, a lot (not saying all) come from some kind of money or all ready have wealth- like how Bill Wanrooy launched Revision skis after already making some money in the dental industry.
Like have you ever walked through a city or ski town and seen a random ass art gallery with no one inside? Rich people will buy them so that they can host events and sell art, even if they lose money operating it, or rarely turn a profit selling anything. They have plenty of money to fall back on, so it's more a hobby than a business.
Again, not sayin it's all of small ski companies, but it is a significant percentage. There are plenty of companies that started out pressing skis or printing t shirts in their garage or a rinky-dink little warehouse. But a lot already had money to begin with and started a company because skiing is something that they enjoy and wanted to be involved.