Its been an evolutionary process to become an empire. The need/desire for growth and acquisition or control of resources (oil, etc.) played a large role. Throw in the dollar as reserve currency, Nixon taking the USA off of the gold standard, the implosion of communism, and the mobility of capital, and you end up where we are; a nation that consumes more than it produces. We have replaced a production based economy with a financialization based economy. Managing an empire is essential to keep the system on life support.
You don't take down an empire via the ballot box. Ron Paul types don't get voted into office with a mandate of taking down the system. If you think the establishment hated Trump, that doesn't hold a candle to what it thinks of a libertarian. Empires generally die either as a result of militarily defeat, internal revolution brought on by social collapse, or economic implosion (USSR). Usually there is some mixture of two or even all three elements.
I liken Snowden to someone who joined an organization under the perception he was serving the country and then discovered he was in essence supporting a mafia and wanted to escape, blow the whistle, and also preserve his life.
Edit: To further illustrate, you might consider Tom Cruise as a young lawyer in "The Firm." Or for a real life parallel, how about Pat Tillman, the former NFL player who gave it up to fight in Afghanistan, only to figure out he was being used as a pawn in a corrupt game prior to be taken out by friendly fire and then used as a piece of propaganda.
People serving in the armed services don't see it this way, understandably. If they did, there would be no military. And while I believe the members of the military take an oath to protect the Constitution (I could be wrong, but I think they do), and enlist with the expectation of protecting the country, that isn't how they are being used.
A normal thinking person thinks spending trillions of dollars over the past 19 years in the Middle East has been a big waste of money and stressed the financial health of the country. But an insider who makes a living via government contracts, a large shareholder of Lockheed-Martin, a corporation with eyes on developing resources, and so forth, would rightly perceive that the empirical adventures have been wildly successful. Trillions of debt paid by others (or in the future) have enriched them greatly with minimal risk to themselves. This is the true face of empire. Making the world safe for corporatism at the expense of the ordinary person.