1. The modern libertarian movement is very young. It's roots can be traced back centuries, but Austrian economics and libertarian anarchist theory did not reach it's maturity or enter the public consciousness until the 1970s. If you look at where the libertarian movement was in 1970 and where it is today, you'll see that there has been exponential growth in a relatively short period of time. I appreciate that you are curious about AnCap theory, but I really think you should be focused on considering whether the theory is true first and foremost.
Given the madness of contemporary times, ideas that are true and virtuous are not necessarily being embraced by the masses. Revolutions take time to catch on. The modern libertarian movement is only a few decades old and we're up against more than a century of deeply ingrained propaganda that we have to dislodge from the public consciousness.
2. I completely agree that the US military empire has spread nothing but death and destruction across the globe. Any notions of "spreading freedom" through government force are nothing but canards to bamboozle the public. It's about military arms sales, mercantilism, and ambitions of global domination. The humanitarian justification for war has always been a shallow and transparent pretext.
Yes, many democracies have a bill of rights, but I don't think you could argue that the voluminous writings of our founding generation weren't somewhat unique in that they were informed by Enlightenment-Era classical liberal thinking. School children are still regaled with tales of the Revolutionary War, and how our patriotic forefathers fought for independence against the British because they wanted to be free. There are many countries that have nothing similar to this as a shared heritage. Some cultures have nothing but centuries of brutal warlords and socialist misery to look back on and the ideas of Natural Rights and the market economy are simply foreign to them.
I wish you all the best in dealing with your immigration problem in Europe, but I won't be voting for Trump in 2020. I very well may not vote at all, barring an exceptional libertarian candidate who's a lot more impressive than Gary Johnson.