None of my coworkers know I have a side gig. I don't want it coming back around to my manager.

I've had a side gig at every job I've ever had. Been in industry for 30 years. In all that time, I've only ever told a single coworker and that was because he also had one.

If you work in software you and your coworkers probably have never needed to run a side-gig to make ends meet. No offense, I am right there with you, so I think it is sampling bias.