Should it be a legal requirement to earn a minimum amount before you're allowed to own a gun?

The most common argument for gun ownership is "I need a gun to protect myself against criminals". Now since the poor make up the vast majority of criminals, it makes sense to ban poor people from owning guns. Poor people are usually poorly educated and often make bad choices.
If you set a fixed income level for gun ownership you immediately take them out of the biggest risk group. Without the risk of being a victim the level of gun ownership will naturally drop at higher levels.
Should it be a legal requirement to earn a minimum amount before you're allowed to own a gun?
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