There is no climax to Waiting for Godot because the purpose of the play is to demonstrate that life itself has no climax.
Climax is the turning point of a play. Since there is no turning point, and no change, there is no climax. The play does not follow a traditional story structure. It is circular in nature. It begins where it ends.
Waiting for Godot is a play about nothing. It is about two men who hang out waiting for someone who never shows up. Yet in all of the “nothing” there is a striking meaning. Life is meaningless in and of itself. You have to bring your own meaning to life. This existential idea has to be explored through a unique existential plot device.
The tears of the world are a constant quantity. For each one who begins to weep, somewhere else another stops. The same is true of the laugh.
We are who we are. It is what it is. That is the message of this play. Your interpretation is the message. You have to bring your own meaning and catharsis, your own climax, to the play.