The whole creator internet is obsessed with growth — new followers, new traffic, new leads. Meanwhile the most profitable audience you'll ever have is sitting quietly in your customer list: people who already paid you once and would happily do it again if you asked.
Why they convert so well
An existing buyer already trusts you, already knows your work is worth money, and already got a result. Every objection a stranger has, they've resolved. Selling to them is less persuasion and more a friendly heads-up that something new exists.
Stay in touch on purpose
This only works if you can reach them — which is why capturing an email at purchase matters so much. A customer you can't contact is a one-time sale; one you can is the start of a much bigger number.