What is the hardest part of balancing your mission's sustainability and your mission's purpose?

To be forthcoming, I'm conducting some market research as part of a mission to better align for-purpose and for-profit incentives. I don't yet have a firm idea of what the product is going to be but would really like to learn from social entrepreneurs:

1. What is the hardest part of making trade-offs between for-purpose and for-profit motives?

2. Are there any frameworks or thought processes that helps guide decision making?

3. What kind of circumstances leads up to the competitive trade-off?

Of the people I've talked to so far, common wisdom suggests that it's difficult enough to optimize for a single variable much less two or three i.e. incorporating your values vs. chasing profit, so it's best to not worry about it too much.

What do you guys think?