Living on assumption and promises is more like spending money you haven't received. People can make promises but how sure are you that the promise will be fulfilled.
One about depending on someone promise, is that the promise can manifest into two way, which I believe that before someone will promise you at it know your qualifications or capacity before it will fulfill any promises, and secondly "note" that not all promise that is real, some promise is a strategies to feed you with what you want to hear and discharge you with good manners, using political promises to justify these, a politician will come to you and promise heaven and earth in the name of you supporting he/her to be able to occupy a political position but after been elected in office it will fails to accomplished the position, so I believe that if promise becomes accomplished its depends on the individual who wants to render help to you, while people do not help people because of their character other way the parents of the person soliciting for help has done him before it get elevated, so that's one of the major factors while some people withhold their help to people.