The difference between “how” and “why” doesn’t seem very meaningful to me. For example- why does water boil? It boils because molecules gain enough energy through heat to transition states.

In that same sense, OP’s question

why there is something instead of nothing.?

There’s a non zero chance that we eventually understand the mechanisms behind the big bang and can explain how nothing turned into something. Therefore we will be able to explain the why, no?