Re: defense: yes, too much is spent on the military. I do not mean too much is paid to the ones who serve on the front lines: soldiers deserve to be rewarded for putting their lives on the line for the country. I mean that too much is spent on developing and buying fanciful weapons decades ahead of the next-most-sophisticated competitor, which do not translate into much of a return on investment on the battlefield. Too much is spent on actually fighting wars against people who do not pose a threat to the US.
All that fear-mongering about ISIS and other enemies really is just fear-mongering: the number of American people actually killed by ISIS is miniscule compared to those killed by traffic accidents, or gun crime, or even drowning in swimming pools, lol. ISIS do not actually attack the US in any really meaningful way, because it is a couple of continents and an ocean away. They make tiny little pathetic attacks that would've gone unnoticed if not for news coverage. Fear-mongering about ISIS merely legitimizes them, which is why they enjoy being "the enemy of the US" so much because it gives them publicity and renown for recruiting. The one place where money should be spent to prevent ISIS attacks is in electronic surveillance, counter-intelligence and intelligence. That's where the real work of counter-terrorism lies.
I don't believe "human rights" and "freedom" are sufficient justification for intervention, because power vacuums lead to completely unpredictable outcomes (mostly bad). Overthrowing one evil dictator just means a decade of chaos and then another evil dictator, in a country without the institutions to support the rule of law.
Speaking purely in terms of US self-interest: I suppose one decent reason to go to war is to take natural resources from other countries (e.g. oil). Maybe scare other countries into paying protection money or something? I'm sure some sort of gunboat diplomacy could be worked out.
Regulatory capture of government by private corporations (bank bailouts, wining and dining congressmen, revolving-door hiring of ex-politicians: of which even Obama is guilty now it seems!) is a huge problem and people need to "drain the swamp" (but Trump isn't going to do it).
To some degree I think most of the core of the Democrats have also "bought in" to the establishment, just probably less-so compared to the Republicans. The two-party system and voting might feel cathartic but if I were an American I'd feel pretty despondent about any change ever being wrought. At least the overall average wealth of the country is very high, so most above-average Americans can enjoy pretty good lives (too bad for the poor Americans though).