There's also an often-overlooked issue, which is that some of the crowdfunded treatments are for things deemed "experimental" or whatever other label and thus not covered for even an insured person. This situation exists in both public and private healthcare systems. I'm not arguing in favor of a for-profit system with this, but people often miss this when they haven't personally run into uncommon health problems.

If a treatment isn't approved yet, you can usually submit a request for getting it paid.

You need to show that it has a chance of working (literature etc...) and it will be reviewed by a doctor from the "Medical Service" which is independent from the Health Insurers.

If they decide it should be paid, it will be paid (which is most of the time the case).

Otherwise you can go through the social courts. (No court costs for the insured person. You can get a lawyer reimbursed if you're poor)