I understand she had a pact with herself that she would die after the money ran out, but why didn't she just leave it to her son? He seemed fairly helpless and unable to face the world on his own he probably doesn't have a well-paying job.
shareShe gave away the money because she wanted to rush to the end.
She knew she was going to die in Paris. As in - why postpone something that she already decided?
This character was a woman of action. Like her life was continuously full of events, of trips to Vail, living like the high-class socialite she was. So she was used to living in a rush, she was experiencing a high by doing all these things and she decided that life was not worth living at a slower speed, with lesser possibilities.