I totally agree with what you said except the reason
(yours: greed, mine: ideology).

When we realized all presidents of USA share SIMILAR belief
on international issues, we can easily understand their foreign
policy, no big difference, the little difference is:
Dem. side has to care their supporters' tolerance
(no-war-peace-lover, and, love-here-love-there, and,
all-green-to-protect-the-globe), as a result, they drop
a few will-be-expire bombs, Rep. side insist on
that they are going to offer the best to all over the world,
as a result, they invade other country.

Dem. and Rep. are all Americans, their similarity is
much much much more than their difference.