I would have to know exactly what Ronald Reagan spent money on vs. Jimmy Carter. Carter was one of the most inept presidents in American history (particularly as to geopolitics - read Iran - and as time has gone on he has only become a bigger lunatic and whore). At the cost of what?
In contrast, Reagan, as a direct result of his efforts and spending, destroyed the Soviet Communist Empire. Ending the Cold War. Something that NOBODY, certainly nobody on the Left, and even "realists" on the Right, thought would ever be possible. Creating the "Peace Dividend" that Clinton was able to take advantage of.
I don't understand your question. At the "cost" of ending the Cold War. At the "cost" of ending (or at least significantly minimizing) Communism as a meaningful worldwide ideological force. Which, no doubt, some so-called "Progressives" did see as a real "cost." (Boohoo to them). However, given the vicious totalitarian nature of the Communist movement, all rational people (Democrats and Republicans) saw this as a benefit. Not that sympathizers still don't exist, including among some that President Obama sought to appoint to Executive Branch positions, and including some Latin American strong-men. But as a global movement, it is fair to say that Communism is dead.
Now, thanks to Ronald Reagan, the bullsh*t mask has been ripped off KGB thugs like Putin. It was the mask
that Communism always relied on, the idealistic ideology wholly disconnected from reality, the noble rhetoric divorced from oppressive practice. Of course, Bolshevism as professed by Lenin from the outset justified its totalitarian "means" of the Dictatorship of the Proletariat based on the never-to-be realized Utopian "end" of a Worker's Paradise, but this mask duped a lot of gullible well-meaning people (particularly in the 1930s and 1940s) ... with their legacy continuing into the 1960s and beyond.
For those of you who are too young to remember, because you take the fall of the Soviet Union for granted, as a historical fact, I can assure you that many folk, on the Left, in the Middle, and on the Right, never saw the fall of the Soviet Union as a realistic possibility. Including Henry Kissinger under Richard Nixon who preferred the notion of accepting the existence of the Soviet Union under the approach of Detente. Many, including Republican "realists" criticized Ronald Reagan for his "naive and simplistic" vision of the world. Many mocked him as nothing more than a "Grade B movie actor reading lines." Even more significantly, respected commentators trembled that Reagan was making the world far less safe when Reagan characterized the Soviet Union as the "Evil Empire" and when he advocated a missile defense system (idiotically labeled "Star Wars" by his critics).
Yet it was Reagan's idealism, in the face of these wrong-headed critics, that directly lead to the collapse of the Soviet Empire and the freeing of Eastern Europe.
Today we are faced with an ideology every bit as evil, indeed arguably far worse, than Communism, in the form of Radical Islam. Because by its very terms, it does not even pretend to don the mask of secular Utopianism and Egalitarianism. Rather it views oppression as a positive ideal. Horrible oppression of women, oppression of religious minorities, oppression of alternative points of view, oppression of democratic sentiments, and so on. And yet, many on the Left, the very folk one would expect would be most offended by the tenets of Radical Islam, do nothing, and say nothing. Instead, they pander and advocate appeasement. So used to hating America, they are, that they can't bring themselves to express criticism of America's enemies. Even when those enemies are no longer the noble Communist Workers of the World.
Fools, they are. And Hypocrites.