6 months: Regularly covering server expenses (which were ~$50-100/month at that point).
18 months: Would have paid for me to live nicely on the beach in Thailand.
30 months: Would cover my rent (and nothing else) at a nice apartment in a major city.
40 months: Passed the monthly take-home pay from my first (non-software) Engineering job out of college.
60 months: About what I'd have been making had I stuck with that first job out of college for 10 years.
80 months: Roughly a Senior Dev salary anywhere but the Bay Area.
As I noted a few years back for the first version of this list, this is for a SaaS subscription product that I built with the explicit goal of having a low-level income stream that I didn't have to put much time into. Early on, there were periods where I worked 80 hours or more per month to get the infrastructure ticking away to my satisfaction. These days, it requires maybe six hours of my attention each month.
This year, though, I've been back to full speed (meaning high single digit hours per week) building out and releasing a bunch of new features.