If a situation or problem boils down to something, that is the main reason for it:
ある状況や問題について boil down to something と表した場合、
その something が主な要因である。
Collins English Dictionary の説明では
If you say that a situation or problem boils down to a particular thing or can be boiled down to a particular thing, you mean that this is the most important or the most basic aspect of it.