I have recently been re-watching Simon Sharma's History of Britain and it reminds me, in places, of other histories I have read of Rome, Greece, Persia and even China and India. They all begin in the same manner, and they all end up going down the same route to collapse. The key elements always seem to be the same, first is expansion, usually driven by ambition (though frequently disguised as 'trade'), then comes the opportunistic building of personal wealth, fiefdoms and power bases, followed by a period of consolidation. Then greed, usually for power and wealth sets in, generally as those who first established the situation make a little room for the second and third tiers of society and allow them a small share of power or wealth.
These 'lesser' magnates are generally the root of the problem. They envy everyone above them and conspire to grab as much of that wealth as they can - often hiding behind the mask of 'striving for a better dispensation for those less fortunate than themselves. The reality is that they generally take to themselves power, and with power, wealth, or at least the access to great wealth for their friends and supporters. In the process they use and abuse the populations they have taken control over. Add in a rich mix of totally unscrupulous adventurers to be found in any society, and you have the seeds for the fall of any empire ready grown. The signs are there in every society, there rises an 'elite' class that subsume to themselves the key positions in government and the supporting bureaucracy, academia, the media and information sources. Then they, in their turn, take care of those most useful to them (usually people from the same 'elite' class as themselves) in key positions in commerce and industry.
One finds them using many, many ideological cloaks for their real agenda most of them very attractive to those remote from power and the sort of wealth these elites have at their beck and call. The bottom line is that they control the access to the type of education they enjoyed, they are also gate keepers to the sort of key positions they award themselves and their friends, and though they give every impression (to the gullible) of being concerned about this or that section of any community, the reality is that they will sacrifice anyone and everyone to remain in power and to keep the wealth they have accumulated. If, at some point, there were perceived to be an advantage - say the acquisition of technology from aliens - that gave them some major advantage, there would be little hesitation in sacrificing the greater part of the human race (out of sight of TV and the media) in order to obtain it. Study the wider origins of the first world war and it quickly becomes apparent that there was a substantial "war party" in Britain manipulating any and every situation because they perceived that destroying Germany and regaining a dominant position in Northern Europe would boost trade and industry - and profits. German trade and industry was 'stealing' the market and had to be destroyed. (See the reasons Britain insisted on all goods imported from Germany having to be labelled 'Made in Germany'. It backfired. It came to be seen as a mark of high quality.)
Plato wrote at length about this trend toward the amassing wealth and power in a small group in his treatise on government "The Republic". Frankly, we should make it compulsory reading for everyone. I suspect, however, there will always be those who have the ambition, the drive and the Machiavellian streak in them, to delude enough people to support them in whatever they wish to embark on.
Long ago I was taught to look behind the ideology, to break it down and ask the important questions such as "who will decide what is fair? Who will apportion the rewards? What will they get if this comes to pass?" It is frequently informative.
As Simon Sharma has reminded me, the British Empire was supposed to be benign, based on mutual support and mutual trade. It failed because the men of power decided to plunder the treasuries of the colonies and the subjected peoples. India was turned into a fiefdom for the sons of the wealthy and for 'adventurers' with the wit to run what would today be termed fraudulent scams. When the colonies demanded (like the Americans in 1776) more say in return for their taxes, they were, if not vilified, at least treated with contempt. And, when the colonists became too inconvenient, or a hinderance to the latest schemes in Whitehall - they were, in many cases, thrown to the lions.
It will not end there either. The current political elites in the western world are already shifting their (and our) wealth to new ventures in new nations. When the time is right, they will abandon their current crop of 'beneficiaries' and move on. Since they also control the media and education, they will continue to blind a majority to the reality of the world they have created right to the last.
Sadly, they'll probably get away with it as well.