Increased defense spending actually makes the US less, not more, safe. Everyone we're going to fight is prepared for an asymmetric, cheap war. We're vulnerable in how much they can make us spend to wage that war. A million dollar patriot missile to shoot down a cheap drone, etc.
But also look at Ukraine. They are punching well above their weight with asymmetrical tactics, but Russia is not defeated.
Drones and other autonomous, cheap weaponry changes a lot. Smaller states and non-state actors can inflict much more serious and expensive damage now more than ever.
Large weapons still matter though. If we ever were to enter an existential battle you would quickly see how big, expensive systems can still be advantageous. I am sure people will take issue with this comment but look at the relative restraint of Russia in Ukraine or the US in Iran vs, say, WWII. Modern morality prevents such scale and tactics until it does not. Then suddenly what matters are big weapons and the huge supply chains powering a war machine.
Both the US and Russia are also pivoting heavily towards drones, and they've been developing them for decades. Yes we have big, expensive weapons programs but we also have a lot of stuff ready or soon to be ready which is much, much cheaper.