The Cold War didn't end because one side had more bombs; it ended because Gorbachev chose to relax his government's rigid hold over his own people and inadvertently triggered a revolution. And it ended because the Soviets' military buildup had bankrupted their nation -- something that probably would've happened to the US as well if it had gone on much longer.
I agree with most of your assertions about the Cold War, but am fairly certain that the United States was not in any danger of being bankrupted by a Cold War that continued along the same lines as it had in the 70s, 80s, and very early 90s.
This chart, which delineates American defense spending from 1794 through last year (both per capita and as a percentage of GDP), demonstrates that the 1980s high never exceeded defense spending during the economic boom between World War II and Vietnam (indeed, in terms of GDP, it was generally half as great or less). The problem that we encountered, fiscally, was not one of spending beyond our means, but of failing to pay for what we spent - much easier to remedy than the Soviet problem (by 1990, Soviet GDP per capita had
fallen to between 36% and 43% of that of the US).
Further, and more on topic, discussing defense spending in terms of tanks or the Cold War when considering Starfleet is highly misleading. Armies are expensive in a way that navies are not (air forces are similarly expensive, but for different reasons). The high recurring costs of personnel-intensive formations are a far greater burden than the similar one-time costs of naval vessels, even when coupled with comparatively low naval manpower costs (the naval equivalent of an Army division has between 7500 and 8000 personnel, where the Army division has about 25000). Ships are also built to last in a way that ground vehicles aren't; a modern capital ship can be expected to serve for about 50 years.
As the chart linked to above shows, American defense spending has been a minor part of the economy whenever the country has not been burdened by the maintenance of a large Army - regardless of the size of the Navy. In 1914, for instance, the US Navy's battle force consisted of no fewer than 37 battleships, none of which were even 20 years old, along with an appropriate number of smaller supporting craft (cruisers, destroyers, etc.), despite defense spending having reached 2% of GDP in only one year of the previous fifty.
Naval spending also offers civil utility that military spending does not. Naval vessels can be - and often are - used for humanitarian purposes, providing relief, transport, assistance, etc., for diplomatic missions, and for exploration and scientific research (as the somewhat improbable use of the Defiant demonstrates). Only the largest dreadnoughts* and the smallest patrol craft (generally those focused on interdicting small craft, submarines, and mines) are of little use outside of wartime. Ships are not tanks, nor are they infantry divisions.
*Of course, in Star Trek, the Galaxy-class is the closest equivalent to the dreadnought battleship - and it was specifically designed to be of great use outside of combat.
