I don't think it's that hard to defend. That people like us emerge accidentally is the default assumption of most working scientists today. Personally I find that a lot more likely than that we are living in a simulation.

And even if you think that it is more likely that we are living in a simulation (I don't, by the way) there's still the question of how the simulators arose. I'd prefer not to make it an infinite regress. Such an approach veers dangerously close to unfalsifiable theology. (Who created/simulated God? Meta-God. Well then, who created/simulated Meta-God? Meta-Meta-God. And who created/simulated Meta-Meta-God?...)

Sometime, somewhere there's a start. Occam's Razor suggests that the start is our universe, in the Big Bang, and that we are not living in a simulation. But even if we are living in a simulation, then someone is not living in a simulation.

I also think there are stronger, physical arguments for assuming we're not in a digital simulation. That is, I think the universe routinely does things we could not expect any digital computer to do. But that is a subject for another post.