A link costs more than it returns the moment the effort to get it (outreach, content production, payment, or sheer time) outweighs the realistic value it will pass. The line is effort-versus-realistic-link-value, and it is crossed most often by low-relevance links, low-authority links, nofollow links chased as if they passed equity, and one-off links from places that will never move a ranking. Chase the links with real return, and drop the rest without guilt. The “build as many links as possible” mindset ignores this line entirely and burns resources on links that do nothing.
Realistic value is the figure to estimate before you start, not after. A link is worth pursuing when it comes from a relevant, reasonably trusted site, sits in editorial context, and plausibly contributes to how Google sees your authority on the topic. Strip those qualities away and the value collapses fast: an off-topic link, a link from a site with no trust, or a link buried on a page no one reads passes little or nothing, regardless of how much work it took to land. Be honest about which side of that estimate each opportunity falls on.
Effort is the other half of the ratio, and it is easy to undercount. A single placement that demands weeks of negotiation, a custom article, or a payment had better return real equity, because the same hours spread across cheaper, higher-value targets would do more. Nofollow links chased specifically for ranking equity are a classic loss, because they were never going to pass it; they may still be worth pursuing for traffic or brand, but not on a ranking budget. Name the goal honestly so you are not paying ranking prices for non-ranking links.
So weigh each link before you pursue it. Estimate the realistic value from relevance, authority, and context, estimate the effort to land it, and pursue only where value clears the cost. When a link demands more than it will plausibly return, walk away and spend that effort on a better target. Discipline about the ratio, not link volume, is what makes a link campaign pay.