As the Daily Mail reports: "SpaceX founder, Elon Musk, wants to send a MILLION people to live in glass domes on Mars within '40 to 100 years'." I hope Elon lives long enough to partake of his dreams himself. What better way to get into the (future) history books than "leading the charge" oneself.
Of course, if the current projections as the size of world's population by the year 2050 are even vaguely realistic, then there will already be close to 5,000 million people in Africa alone. That could then be approximately one third of the world's population of, perhaps, 15,000 million. From that perspective, a million (more or less) inhabitants on Earth are not going to make a significant difference to the total of the human population on this planet.