For the entrepreneurial people, it’s rarely about the $$ amount.

The money made from a side project feels x100 better than a salary in increase.

1k a month passive profit from a SaaS is worth a lot more than 12k extra salary. A full time job requires full time labor to continue producing income. Whereas SaaS hopefully almost none to maintain it, has a better growth potential than your salary raises, and when you're tired of running it, it's an asset you might be able to sell to somebody else.

It's vary rare to get a SaaS that requires no ongoing development.

That makes sense until you realise you've spent 10 years working and you'll have to work full-time for the foreseeable future because you don't have a 5k monthly (quasi) passive income

Passive income is rarely passive.