So because we exist, that means the universe is fine-tuned for life or there's just so many of them that we ended up in a one that's randomly good.
Maybe something else is happening, which is that life... finds a way. Maybe there are far more possible combinations of constants that allow the existence of life than we think because our definition of "life" is so narrow.
At any rate, the concept of our universe having a purpose, and that purpose being life, isn't supported by the fact that almost all of our universe is extremely hostile to life. If "someone" - not god but maybe god - designed a universe where life was supposed to thrive, why put so goddamn much of it out of reach, and fill all of that with radiation and hard vacuum?
In other words: If this is a universe tuned for life, it's not a very good one.