* It helps me focus on the content my users need the most, and see what triggers donations.
* It helps me catch and diagnose traffic dips, and react to them.
* It helps me catch and diagnose unexpected issues. For instance, caching changes broke a component that accounts for 30% of my revenue. It would have stayed broken for a whole month if I didn't see the dip in events.
I will replace Google Analytics soon, but even as a tech-savvy person, it's a dreadful task. Google Analytics is free, simple, and incredibly reliable. Setting up your own self-hosted alternative, or paying a monthly fee for an alternative is a lot less desirable.