I doubt there is a market for it as there are many already well known people, authors, or experts that have written about the two subjects mentioned.
eBooks can be written (for very little or no cost) on your personal experience or any subject the problem being marketing and attracting a readership at all let alone a readership that wants to pay (e.g., sales). It doesn't "hurt" to write about what you know just don't have unrealistic expectations as the market is tough to break into in any substantial way. Of course it is possible, but the odds are great.
There's a way to get off drugs and not only stop being depressed, but be happy and it doesnt cost a cent...all that you have to do is be willing!