The fine tuning argument for God is circular. It assumes that life, and more specifically intelligent life, is special. If so, it can only be because it is special to a supernatural entity that cares about it, i.e. God. It thus assumes that which it is trying to prove. If there is no God, then life and intelligence are not special. So what if the universe had to be finely tuned to produce it: some set of conditions had to obtain, and they just happened to be the ones that were congenial to the emergence of life and intelligence. This is one version of the "so what?" counter-argument to all arguments for God. The more interesting question is why any universe exists: why is there something rather than nothing?
There are quite a lot of responses to that. The most basic is that nothing cannot exist, as then it would be something. This comes up in relation to death, as some people say, 'maybe there's oblivion'. Well, that can't be, I suppose it might be something rather empty and barren. But that's not nothing.
There are also some interesting ideas in physics and maths that nothing would actually be highly unstable, and would rapidly turn into something. However, the first nothing is perhaps not what we mean normally by nothing.
And then there are all the descriptions of unstable vacuums, which are rather similar. I think quantum mechanics has revolutionized this, with its talk of bubbles of space and time forming spontaneously.
And as BeRational says, we also don't really know.
(One of the other interesting spin-offs is that there is no stability in nature. Well, things like the sun appear stable, but not in the long term. This relates to the old argument from motion - how does motion begin? Well, in an unstable universe, everything is in motion, and rest is unusual, or merely apparent.)
