@lain it definitely has a genetic component.

people with high neuroticism, who experience anxiety a lot, might be more inclined to invest due to a general negative outlook in life. or they are extremely high in neuroticism and might push it away as something too difficult to think about. or very low in neuroticism thinking it will work out fine.

also conscientious comes into play: people more strict with themselves will be stricter with money. maybe because they experienced past adversity.