Mars looks like an awful place to live in. There's nothing there but an endless reddish dusty wasteland. I doubt many people could face spending the rest of their lives on it. Colonizing mars with a significant population needs a significant number of people to volunteer to go there, and I doubt there will be enough volunteers.
I think there is already many volunteers that are being tested to determine which ones get to go to Mars.
Yes but to make a significant population on mars needs tens of thousands of suitable volunteers and I'd be surprised if that number of people want to spend their entire lives there.