TLDR her dad works in finance, moved the family to Nashville, and supported her career at every step. So she very much got carried by her parents even if they didn't buy her fame.
Given the Music Industry's history of insidership and hand selecting artists for the highest level of promotion; I think the lack of "smoking guns" such as her parents mass buying her albums or paying off producers etc just shows how inorganic and corporatized popular music is.
The fact that she's alt-country is the smoking gun. WWE is less fake than Country Music.