Why preserve dharma?

Why do we need to preserve uphold & perpetuate dharma? Eventually humanity/human-civilisation will be long gone and along with it the human aspect of dharma too;but the universe will continue to live. The cycle will be repeated as it has happened in past. Also earth is not even a speck on our own galaxy even, and for the universe our planet doesn't even exist. And whether there is any God/creator or not,all human beings count as a single lot; then why fight with adharma and why preserve dharma? Or may be life might go in a puff with an asteroid shower? Because only dharma will ensure continuity of humanity and human civilisation as adharma is like a pathogen which proliferates but takes down the host with it and goes on to find and consume another host. Though nothing guarantees the perpetuity and eternity of intelligent life on earth it has infinitely greater probability of doing so if true sensibility, maturity,peace,righteousness,equanimity and harmony prevail at large,if not in absolute,to say the least. And the continuum of intelligent life on earth till perpetual eternity cannot be guaranteed by violence, lust, consumerism, fanaticism, death, injustice, proselytisation, dogmas, faith-mongering, conversions, deception, cunningness, savagery, barbarism, free-market, destruction of nature, totalitarianism, greed, corporatisation, exploitation, slavery of any kind, colour, creed or hue. All this will sure lead to planetary suicide of earth,which is actually happening. And what do we achieve by the continuity of life on earth? May be nothing. Or may be, there's a great probability that, eventually we transcend the physical universe and go on to meet new universes to realise the physical/material dimension of aham brahmasmi, tattvam asi, prajnyAnam brahmam & so'aham asmi. Or even better, may be we go on to spread life itself newly afresh on different planets or even create new life forms and for better sow them in newly created planets and perpetuate the eternal continuum of life even after we are long gone while the newer lives continue to pursue the quest. Its so exceptionally rare and fortunate to have life on this planet and universe as we know and we cannot let ourselves waste this opportunity by permitting adharma to prevail over dharma. And before an asteroid shower hits us we should be technologically advance enough to shield life itself which demands the continuity, progress and advancement of life,again!