In summary, the US doesn't need to proactively attack anyone because military size and strength prevents an attack by other nations.
Wrong.
America's enemies will grow in military power if they are allowed.
You think that the answer for America to remain safe is to continue to also grow in military strength.
But that is short-sighted. Common for people like you. People with very limited intelligence.
If the answer were only to always remain much stronger than the entire group of enemies, while letting them grow stronger, the USA would eventually have to turn the entire North American continent into one massive military compound to be properly protected.
No. That is stupid. The USA wants a high quality of life for Americans. Not a massive, country-wide military base housing each and every American.
The better solution is to use the current levels of military strength to continuously keep the military power of the enemies at an acceptable level.