Yes, I think it's just this syndrome thing. Obviously, not historical scars that runs through the veins of many given country's citizens. Not money, treasures robbed or economy ruined by those oppressing which now means they're bigger. Lunatic post that smacks of fake confidence. I mean, you do know you're seen as small brothers to Brazil
(assuming you're from ARG)
Can only speak more for us, Poles, though. I genuinely haven't seen any Pole feeling inferior to the Germans. If anything, quite the opposite. We're now seen as a country on the up whereas them...
Also, I wouldn't call 'the bigger of the two' citizens open-minded and relaxed but simply being used to comfort and luxury, being unable to understand the mentality of the opressed where you had to fight hard for everything. It may be mistaken for backward, full of complex attitude but actually it should prove vital in the upcoming years. The economic prognosis for some of those countries you've mentioned are actually pretty good. Who knows, in 30 years' time let's say, some of those pairs can read different (Sweden's will in a decade at most).