It may be a lose-lose situation for us. But it's not much different for you either. Considering that throughout history, various gods have been described by various tribes, it could be possible that any of those exist. And if only one of them is the real god, then there's a great chance that your god does not exist, or was just made up.
If according to you, atheists gain nothing, then according to me, people who pray to the wrong god gain nothing too.
The Hindu Trinity represent different aspects of Brahman. Brahma has the power of creating, Vishnu has the power of sustaining, and Shiva has the power of destroying. All 3 together embody the properties of Brahman, who is therefore Supreme.
Why do you think Brahma, Vishnu and Shiva do not exist?
The belief that "Various gods are various interpretations of same thing" is as baseless as the concept of god itself. Also, it raises more questions than answer them. For example, why would this singular god manifest himself as Yahweh or Allah, and proclaim that he is the one and true god, and that there are no other gods(which is himself)?
I think this is a stupid explanation, invented by people who want to avoid the possibility of whether these different gods all exist or not.
The truth is indifferent to your perspective. Something either exists or not. Gravity will not cease to exist just because you have a different perspective of it.