From our experience, we have worked using various models of publishing:

1. Reselling for other publishers directly (zero risk / low reward)
2. Licensing for translation from other publishers and selling for ourselves (high risk / high reward)
3. Authoring original books in cooperation with authors (moderate, shared risk / high reward)

In all cases, the main make or break factor for success is market acceptance and need of the book topic. This defines sellability of the published items and how rewarding are they. Selection of the books to be published is usually based on estimation of community interest based on field of speciality of our community. This estimation is not always accurate due to difference between expectations and actual sales size. Other factors that need to be taken in consideration are visibility of the published item within the market, and what purpose does it serve which will make it attractive to readers.

The main risk with publishing is that it doesn't fail fast, it takes long time to prove success or otherwise, and this needs to be accounted for upfront so that negative consequences don't accumulate over time.