LTV-Driven Channel Choice
LTV picks the channel, not the other way around. If no channel runs profitably for two years, you have an LTV problem — expand the offer until the math works.
The channel you should pick is decided by the LTV of the customer you're acquiring, not by the channel that "feels right" for the category. A $50k LTV fertility patient justifies a content engine, a credentialed-reviewer team, an email nurture sequence, and a sales call. A $200 LTV skincare customer can only justify a directory listing or a low-cost ad unit.
The diagnostic is to take CAC and divide by LTV, then ask: at this ratio, which channel can I run profitably for two years? If the answer is "none," you don't have a channel problem, you have an LTV problem, and the right move is to expand the offer until the math works — not to keep optimizing a channel that can't carry the unit economics.