So would you describe the Maginot line as a good investment?

Obviously not. Germany noticed lines have ends, and just went around.

So you're saying that a nation without a large standing army can build a new force well suited to exploiting weaknesses of its adversaries who spend substantially on maintaining investments in defense which contain those exploitable weaknesses?

One might go so far as to say that not having a strong standing army for an extended period of time actually proved militarily advantageous for the Germans in 1940 when their new army outmaneuvered an obsolete one.

I was responding to “The moment one country starts militarizing in a world without militaries, you know their intentions and can start remilitarizing to counter.” Lack of a military is quite a weakness to exploit.

The Brits abd French actually drastically cut military spending between WWI and WWII

Also, they went around it using, in large part, Czech armor they took when they invaded Sudetenland.