Thank you for your welcome, Susan.
I agree with your opinion that the difference between the two possible meanings of "substance" is vast, and had considered rewriting it to clarify. However, both in my life and in the lives of others I have noticed that many of us try to find something to distract us from the voids in our lives. "Therapy," in this context, refers to fixing the problems in our lives, especially through healthy means. "Substance," on the other hand, can indeed mean substance abuse, as it has on many occasions for me; however, it can also refer to anything that we put into our lives to take attention away from what is wrong with us and our lives. People filling their day with activities that really mean nothing to them, simply to escape the feelings of emptiness that plague them when they stop long enough to take a breath.