I suppose if you play your cards perfectly, are trustworthy, and have some desperation in your counterpart, maybe you could convince that broke man to give you $1 million.
So, the real goal behind effective negotiation is to come as close to achieving your ends as possible and this is done by seeking to understand the other side and gain as much information as you can in the time you have. The other step is to use that information to help both sides come to a happy agreement–but hopefully with some advantage to you (as long as it is an end ethically gained, that is).
The information will tell you what you can get. If you’re trying to get a million dollars from a family that has about $1500, there isn’t much you can convince them of. It’s impossible for them to send you one million dollars. Finding out that limitation will inform you in a way that helps resolve the negotiation suitably.