"A Social Entrepreneur is someone who wants to make a positive change in the world, and realises that they still need to pay for lunch while doing so."
This differs from the capitalist who sees the enterprise as a means to buy lunch, and the philanthropist who is lucky enough to have the means to buy lunch without having to earn any more money.
So why all the talk about lunches?
There is a saying that to "cut someone else's lunch" means to take something out from under them, usually work, e.g., to purposely under-bid on work to take it away from someone else who has a fair entitlement to it. Here's an example that I found in a few minutes of internet trawling to give you an idea of how it is used. (It can also mean to try to hit onto someone else's partner, but that's another story. Here in Australia both meanings apply).
So if you cut their lunch for them, you are doing them some kind of disservice, by taking something that was theirs to do or to enjoy or generally derive benefit from.
This is particularly true for the capitalist for whom buying the lunch is what it is all about: if they cannot derive financial or status benefit from cutting their own lunch, then they have lost something very tangible. Anger or grief may then naturally follow.
But for the philanthropist and social entrepreneur things are different. It is the improving of the human condition that is their desire.
For them, it is a gift for someone to cut their lunch, it really is a free lunch, and then some.
Consider for a moment if some upstart discovered a 100% effective and affordable vaccine for malaria. This would be cutting Bill and Melinda Gate's lunch, since that is one of the great things that they are working on through their foundation.
But I have little doubt when I say that if that were to occur the Gates' would be jubilant with celebration, because someone has gone to the effort of cutting their lunch, so now they can move on to the next thing.
So it is for all social entrepreneurs if they think the matter through: to be out competed in improving the human condition is to receive the gift of days that were otherwise required to work on that venture: they can now move onto the next thing, and celebrate that what they set out to achieve has been accomplished.