I think this problem is partly caused by the combination of wealth and democracy as a
form of government. Democracy works great in the first generation where everyone still
remembers the horrors of the tyranny or the dictatorship that preceded the democracy.

However, in the first world we are already past that stage where nearly all people, who still experienced
these horrors are either dead or too old. The other problem is related to the fact that the easiest
way to get people to like you and to actually vote for you, is to promise them free stuff and
government handouts. This leads to a bidding war between candidates where you can only win an election
if you promise to increase government spending / welfare. This leads to an expansion of the welfare
state, which in turn leads to an increasingly large number of people that live off the government.
After the percentage of these people gets too big in a society, the society is basically fucked.
E.g. in my rather rich European country only 14 % of the people are net taxpayers
(the other 86 % of the population either pay no taxes at all (children, unemployed...) or pay
less in taxes than they receive in other government transfers). This is obviously a huge problem
for the society and my society is not the only society that is experiencing this bad development.

Despite this unsustainable decline of society the system still hasn´t exploded, because of the reason
that I shortly touched upon at the start - the enormous wealth that has been built up
in the previous generations and the general technological progress.

Nonetheless, I completely agree with your post that these countries will experience very bad times
in the future.