It does makes sense from their standpoint though. In their mind, everything they want to spend money on is necessary, while everything the other party wants to spend money on is wasteful.
The missing piece of logic is that the Republicans don't actually want to fund their expenditures. Democrats may be the party of tax and spend, but Republicans are the party of just spend. The former provides back pressure to the electorate, the latter is a recipe for ruining the country regardless of your policy preferences.