For life as we know it, to exist on Earth
Earth had to be at the right distance from the sun, warm enough, but not too hot nor too cold.
Earth had to have a hot core so that the planet is alive and developing everyday. The core gives earth its magnetic field, which shields us from countless radiations.
Earth had to have an ozone layer so that the UV rays from the sun does not fry life on earth.
Earth had to have a moon, so that tidal activity was possible to keep the water cycle active. The moon also shields the earth from astroids.
Earth had to have liquid water.
Earth had to be in a part of space where it would not be hit by a large meteor or comet for a considerable period of time.
It takes a lot of things to come together to make something right, it only takes one thing to be out of place to make something wrong.
To tell someone, something is NOT possible, is very easy; to make it possible is very difficult. Entrepreneurs are people who set out to make something possible. So the next time you think an idea is shit, think about it once more.