SpaceX's Elon Musk plans trips to Mars

Well, I watched a video about Elon Musk (Tesla and SpeceX's chief) plans trip to mars.
He revealed last week a plan to install a colony of hundred people on mars. The price of a ticket for this trip will be around 100 000$, to make this accessible for a lot of people.
SpaceX plans to send a cargo capsule to mars in two years, whithout people. The first human mission on mars could leave earth in 2024 (in only 8 years!) and arrive on mars one year later.

I think this is a very ambitious project but lack of reality. As a professor at George Washington University's Space Policy Institute said, Elon Musk presentation was "long on vision, short on detail". In fact, for the moment, Elon Musk have not the billions of dollars that would be required to put this vision into reality. In fact, to give you an idea, a mission of three to six people would cost between $80 billion and $120 billion.
Morethan, the US space agency NASA, which is studing about this project since years, annnounced his plans to send people to mars around 2030. So if the NASA is not able to accomplish this before 2030, I don't see how Elon Musk can do this with SpaceX (which is a Young company) in 2024.
But I hope he's right, because it'll be a major step forward.

Why Mars?

People would eat it and then they'd need to go further into the milky way.