is there a scientific reason? assuming many alien civilisations exist what would be their interest in surveilling relative primates like us? why not just colonise us?

ive seen recent documentaries suggest that earth is a source of tourism for ETs because it is a rarity in the known universe - for its diverse and beautiful landscapes, flora and fauna. the documentaries also suggest ETs have a vested interest in ensuring humans protect the environment for this reason. how accurate may all this be?