We pay taxes simply because it can help boost the economy, gather funds to build public office, buildings, establishments. It also serves as government funds that intended only for government used such as projects that helpful for the people. Paying taxes is required by the law and are abide to pay for it if not then you liable to be sanctioned by the government.
Taxes are for the boosting of countrys economy and if all the people will pay tax sincerely that is distributed among them equally, the country will become financially strong because the money will regulate and poor people would also get some work and money to meet their basic life necessities. But I dont think that there is even a single government in this world which spends all the tax on her people.