If it's a simulation then it is a simulation of something, for a purpose. Every atom is needed for the simulation and you, and your choices, have an important enough impact on it that you're worth simulating.

It doesn't matter that you have no idea what the purpose is. It doesn't matter that your individual contribution could be almost insignificant. There's meaning there.

The alternative, that the universe is completely absent meaning and eventually everything fades into heat death and nothingness represents a kind of existential nightmare. You can get comfortable with the nightmare and find meaning for yourself. But an external meaning would be a very important philosophical thing.