What does it mean by consent of the government

A condition urged by many as a requirement for legitimate government: that the authority of a government should depend on the consent of the people, as expressed by votes in elections.

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the answer is: must pay taxes on profits

since it is considered as a part of your income, profits from investments is eligible for tax payment.

the tax from your investment could be influenced by how long you decided to sell it. united states promotes keeping your investment for long term period. so, the tax rate for investments that you sell in less than one year is typically higher compared to investments that you sell in more than one year period.

social contract theory, nearly as old as philosophy itself, is the view that persons' moral and/or political obligations are dependent upon a contract or agreement among them to form the society in which they live