Stable income: Somewhat stable

Renting space for parking can provide a moderately stable income stream for most people who try it. Based on online research and my own observations, while there may be fluctuations due to seasonality or location, many individuals consistently earn from this side hustle. If your best friend quit their job to do this full-time, I would say 'You'll be fine' with reasonable confidence. I'd rate it a 3 out of 5 because although there might be sporadic dips in income, overall, it offers a decent baseline of income with some reliability.