Saudi Arabia has a strong army but its economy is weak, based on production of oil which is a non-renewable resource— essentially mining (a source of wealth).
Saudi Arabia has no manufacturing (a source of wealth) and no agriculture (a source of wealth).
By your definition, Saudi Arabia is in good shape with its strong military. Yet, would you want to live there? Would you want to raise a family there?
Saudi Arabia does not even manufacture its own weapons.
A sound economy is a balanced economy, one that has manufacturing, agriculture, and mining. Everything else (even military) is “downstream” (a service) of the primary economic wealth engines.
So a strong military is nice, but ultimately leads to being an unbalanced society (in one way or another) if there is not a sound economy (mining, manufacturing, and agriculture) supporting that strong military.
If you have an economy that is missing one of the three legs of economic wealth, then you have a two legged stool. In particular, a country that loses its manufacturing wealth becomes dependent on, and eventually subservient to, powers (governments or multinationals) that control the manufactured goods that need to be imported to sustain that economy.
Multinational free trade agreements herald the ascendancy of multinational corporate power over national sovereignty.
That power will eventually express itself by government sanctioned physical force.
And that expression of government sanctioned use of physical force would not be pretty.