Well how do you know it is true?
You have a point however has anything been observed to have popped out of nowhere?
Whereas cause and effect, beginning and explanation seems to be fundamental to the universe We work entirely on reason.
However if you invoke the popping out of nothing then you accept the necessity of something in this case the universe. The question then is, is the universe necessary when everything in it seems to be contingent.
Secondly there is the idea of popping out of nothing is that justified? Well we can not be sur that today virtual particles are not accounted for i.e. Pop out of nothing since they might come from somewhere else and have a reason for doing so. You would then be trying to demonstrate that something is unjustified by means of something that is unjustified
I think that that is at least enough the to say that something must be necessary. You are saying that that must be nature, but there are many arguments why that is not so.
Declaring the premise not justified then is itself not justified for we cannot say it is not true.