Genuinely stuck: why is seo important?

people search before they buy almost anything. if you're not there, a competitor is. it's the cheapest customer you'll ever get, it's just slow to get going.

Because it's the one channel where the person has already decided they want the thing - you're answering rather than interrupting. The other half of it is that the work compounds. Stop paying for ads and the traffic stops that afternoon; a page that ranks keeps earning while you're asleep. It's slower and less predictable than paid, which is the honest trade-off nobody puts in the intro paragraph.