Fear of a Capitalist Planet

It's as equally likely that there are 'helpful', 'angelic' aliens out there who would share their knowledge with us and springboard humanity into an era of peace and prosperity.

Wait... what is that equally likely to?

That there are aliens out there hellbent on destruction that take joy to glassing planets with plasma blasts ala Halo Reach (Trivia: The Earth's crust can be glassed like what happens in Halo Reach)

The argument to NOT CONTACT E.T is because of the latter - not the former. It's risk aversion. While the former sounds wonderful, the latter... well the latter kind of sucks. Why should we risk exterminating our very existence to contact aliens on the hope that they are friendly, or at least non-hostile?

Even if the Earth was a wonderful planet where Communism had a realistic chance of working (and not conflicting with human behaviors) - that wouldn't make peaceful aliens any more or less likely than destructive aliens.

As much as I support "Communist ideas" of equality of work and distribution, they fall apart on a city-level due to human nature of self-interest and self-survival. Let alone a country or global level. It's simply not realistic.

Communism doesn't work because it needs a power to enforce it. That power will become self-serving and work in its self-interest over time. It corrupts itself and creates class-wars between the general population and the enforcers, leading to revolutions. Typically bloody.

See:

http://i.imgur.com/bv1BgHp.jpg