Q:

Why has life evolved around oxygen?

Why has life evolved around oxygen? Many lifeforms require oxygen to breakdown bio-molecules and release energy. I think there are two possibilities:

Reactions with oxygen tend to release more energy, so it is profitable to use oxygen for metabolic activities.
It is chance that it got to be oxygen; it could have been anything.

Which is right? Or is there some other possibility?
Edit: Yes, it is true that there are organisms to which oxygen is toxic. But you can't ignore the large numbers of organisms to which it is absolutely necessary for living. Why could it not have been some other molecule? Which property of oxygen drives it to become the most useful in bio-processes?

A:

I think you need to consider that oxygen is toxic to large groups of microorganisms, because it poisons their electron transport chains. 
Strict anaerobes does not tolerate the presence of oxygen at all and as such I would argue that life can survive and thrive without O2.
Also life on earth evolved under conditions were O2 levels were extremely low, in fact when some organisms started to release oxygen into the atmosphere it caused an extinction event (Great Oxygenation Event).
So I think you need to change your question to why did life adapt to the presence of oxygen?

