the money has already been allocated to a budget
The money is added to the budget, but is outside the needed operational expenses of the department. It is created from a baseline of the operational expenses plus the previous year's earmarks. Earmarks don't eat into the operational expenses, it is part of a culture in DC of adding more and more to the budget, over and above the needed operational expense to continue to cover these pet projects. Politicians cop out and say "Well, it is part of the budget anyway", hoping people don't realize that it is part of the budget because of earmarks the previous year, and the year before that, and the year before that, and so on, always nudging the baseline upward. The culture in DC actually penalizes saving money as it lowers the baseline and budgets are cut, so politicians always try to take as much pork as possible. Others like to point out, well it is only 1% or so (after the recent bailout and TARP packages, I would bet it is creeping closer to 10% if you count those..), but even at 1%, dropping that each year would reduce the baseline instead of increasing it. Dropping it 1% each year instead of growing it 1% each year could result in a 20% decrease in the budget over what it would have grown, in a decade.
The appropriations process determines how much money is allocated to a budget. Ron Paul votes NO on these appropriations.
Earmarks only specify how some of that appropriated money is spent.
I don’t think it needs to be any harder to understand than that.