The danger of celebrating high registration numbers with low retention?

There’s a false sense of security in seeing signups tick upward when your actual core product usage stays completely flat.

We used to celebrate traffic spikes from launch directories only to find out those users vanished within 48 hours without touching a single key feature.

Chasing volume instead of actual activation was burning our engineering time on the wrong problems.

If you've run into this trap how did you restructure your core metrics to measure real engagement instead of empty vanity numbers?