This is philosophical difference, not an issue about spending.Many of them were classical liberals. They did not even want the United States to have a standing army. Instead they wanted the government to depend up citizen militias to defend the nation.
It still is.Their reasoning was that a government could never become totalitarian if it had to depend on its citizens to defend it.
I'm sure there was plenty of waste and corruption; it is the government after all, but waste in military spending is more acceptable than waste in entitlement/social programs.So yes, rampant defense spending growth in the Reagan years and the corruption that lead to 700 dollar hammers and 1100 dollar toilet sets was entire the Reagan Administrations doing.
None of this changes the fact that said entitlement programs required massive amounts of revenue, revenue that could be spent on any number of things, including the military.Secondly, payroll taxes pay for Social Security, Medicare, and Medicaid. Those are your big entitlements, and they had surpluses at the time. The problem was rampant growth in discretionary spending during the Reagan years.