People don't become rich just because they are smart. IQ has really no relationship to your wealth. And being very smart does not protect you from getting into financial difficulty. Financial success for most people means more than just income.
Intelligence is not a factor for explaining wealth. Those with low intelligence should not believe they are handicapped, and those with high intelligence should not believe they have an advantage.
A higher IQ is correlated with a higher income, but not with higher wealth.
I haven't seen a scientific explanation, but to a large extent, wealth is determined by inheritance, marriage and the local housing market. Smart people with a high income are also more likely to lose money as active investors or by spending to support their social status.
Stop asking the same question over and over again. You can use the search bar first.