Molecules, particularly organic molecules, are stable or unstable depending on the environment. You ask how life could arise. How clever of you to notice that we don't yet know.
That attitude has always worked before. That is why we don't have technology or medicine or genetic engineering -- because our state of complete ignorance never changes. People who sought knowledge because they had faith that it could be obtained have all failed, died and gone to hell.
"Molecules, particularly organic molecules, are stable or unstable depending on the environment."
The "environment" in question (i.e. that I initially responded to above that got you to quote me out of context) was a hypothetical, fabricated water world in which EVERYTHING changed rapidly.
If you are going to get snippy, at least have the courtesy to pay attention to what people are talking about, please.