That's the problem with drinking, I thought, as I poured myself a drink. If something bad happens you drink in an attempt to forget; if something good happens you drink in order to celebrate; and if nothing happens you drink to make something happen.

This quote is speaking about the potential pitfalls that can come with drinking alcohol. It is saying that if something bad happens, you might use alcohol as an escape from the problem. If something good happens, you might celebrate with alcohol. And if nothing happens, you might drink alcohol to make something happen. The quote is warning of the implications of using alcohol as a crutch in response to both positive and negative experiences.