rethinkinng, don't worry about the whole "screwing people over" bit, that's just one person blowing smoke. In my opinion, if a student is teetering on the edge of acceptance so much that not admitting one person would make the difference of acceptance and rejection, then that student hasn't worked hard enough in the first place. If that student is more qualified than you, then he/she wouldn't even be in that kind of predicament. So don't let the guilt trip get to you and do what you have to do.
Having said that, I noticed you mentioned "financial stability and a fulfilling personal life". That's also my goal as my grad work is aimed squarely at industry work rather than academia. You did not mention what field you are in, but it sounds like you are leaning toward industry work. What is the alternate route if you do not go to grad school? I agree with the others that if your school allows deferrment, go ahead and do that and think it over over the next yr. However, if they do not, I would lean toward the alternate route if it is immediately viable. Based on everything you've said, I feel that is the more suitable course of action.