In theory, a SaaS offering should have economies of scale and should be cheaper than self-hosting, especially if you put a monetary value on the time you spend maintaining your own server(s). However, number must go up, so this may not be the case.
There are a few other factors that may come into play that make self-hosting the more economically favorable option:
- Repurposing old hardware you already own instead of buying new
- Learning skills that lead to a higher-paying job
- Sailing the high seas instead of paying for media