So then what is one's duties to one's country? If I have multiple citizenships, would you say I have to pay my 40% tax in Canada and another 35% income tax in the USA since both tax on worldwide income? It is one's duty to pay 75% income taxes by just breaking $120,000 in income a year? Stupid.
You don't have dual citizenship. The United States doesn't recognize dual citizenships.
It is a duty because you benefit from the services provided. Heck you benefit from them whether you personally take advantage of them or not.