Here’s an article that’s closer to the truth of doing a u-ISV:
The Software Product Myth

In our completely un-contrived scenario you’re now making $2500/month from your product, which doesn’t allow you to quit your day job. So you work 8-10 hours during the day writing code for someone else, and come home each night to a slow but steady stream of support emails. And the worst part is that if you’ve built your software right the majority of the issues will not be problems with your product, but degraded OS installations, crazy configurations, a customer who doesn’t know how to double-click, etc&