A theory is a good theory if it satisfies two requirements: it must accurately describe a large class of observations on the basis of a model that contains only a few arbitrary elements, and it must make definite predictions about the results of future observations.

Why does the universe go to all the bother of existing?

Plagiarism saves time.

There is a very real danger that we will kill everything on this planet now that we have the technological power to do so.

We only have to look at ourselves to see how intelligent life might develop into something we wouldnt want to meet. I imagine they might exist in massive ships, having used up all the resources from their home planet. Such advanced aliens would perhaps become nomads, looking to conquer and colonize whatever planets they can reach.

What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise.

The laws of science, as we know them at present, contain many fundamental numbers, like the size of the electric charge of the electron and the ratio of the masses of the proton and the electron .... The remarkable fact is that the values of these numbers seem to have been finely adjusted to make possible the development of life.