After all, if we fulfill our potential, then the life that evolved on earth will survive the depletion of our sun, and possibly gain the ability to continue to evolve in completely new and different directions separated on other worlds. And if we don't, and instead eventually go extinct, then there's still five billion more years of life left in our sun - time enough for many more new species to appear and thrive long after every trace of our existence and our actions has worn away.
I mean, if you "were" nature, isn't that a risk you'd take? If what you "want," to judge by what happened long before we arrived, is for life to spread to every place it can - from the sea to the land, and from the land to the sky - then wouldn't you want it to spread to the moon and the stars as well? And if in generating the first species with the hope of doing this you "knew" you'd lose about the same number of other advanced species as a meteor or ice age would have eventually taken regardless, wouldn't you still do it?