Brazil needs their energy source. There are more regular Brazilian citizens than people who live in the tribes which might be affected. Brazil is the top country of the world because it is fully immersed in using clean energy, and because there are constantly more needs for the electricity, forming dams is the only way
Damming Amazon.Com would prevent many self-publishing authors from publishing their writings. Besides which, how does one dam a web-site? If by "dam" we refer to blocking the site from the internet, it would certainly be wrong because (including the previously stated) it is a violation of our rights to a free internet.
I think the Amazon is one of the last remaining places on earth that have been unspoiled for the most part on the planet and therefore should not be trifled with. Maybe the earth will become unstable in certain areas if they tamper with the Amazon so they should just leave it alone