NASA has announced the Hundred Years Starship, a manned spacecraft mission to Mars that will leave the astronauts there for good to colonize the planet.
Leaving the Earth permanently I expect will draw countless volunteers for many plausible reasons, not the least of which is an eagerness to escape the failings of this planet, its leaders, and its inhabitants. If given the choice, many would leave. So far, there is no choice.
A mission to colonize Mars and ultimately the entire universe will appeal to many types of people. Wealthy thrill-seekers who can afford to pay their own way and enter the history books won't be hard to lure and will be demanding a seat on the next rocket. Those who feel Earth is a failure will see the mission as a new hope of a better life and future for their descendants, whereas a future here can leave one feeling like everything has been for naught.
It will eventually be a great challenge to weed out volunteers who would do the mission more harm than good: secret saboteurs, criminals, mental defectives, and those will might soon feel a sense of "volunteer remorse" and demand to be sent back!
Regardless of whether this particular mission succeeds or never gets off the ground, eventually the human race will need an exit strategy from Earth, either because we ourselves threaten to destroy it, or an asteroid in our path can't be stopped, or the sun stops shining billions of years from now. Earth has an expiration date, and that can't be ignored.