Are there evidence that shows there are enough people who have the resources to pay for a one way trip to Mars to start a colonization? If there are not, then any near future proejcts won't go further than sending several government-funded professionals to Mars, not enough for a true colony.
IMO there won't:
(1) Altough Rich people want to pay to go to Mars for a holiday if it is very safe (including the return), but most rich people should not want to pay to live on Mars for their rest of life, since it is much more miserable than life on Earth (considering their much high opportunity cost for that). Note: tourism in the far future will be based on existing colony which is needed for lauching from Mars.
(2) Although a lot of people want to spend their rest of life on Mars wigh funds support from goverments, but goverments don't have enough funds for that. In fact, any reasonable vote system will vote the fund for other more meaningful tasks, e.g. development of better rockets for another 100 years to get real low cost and high safety/development of true AI robots or even biological robots to replace human resource for the colonization/solving the existing issues on Earth.
Then even with an Apollo-like project that could send several government-funded professionals to Mars, is there a big enough human resource base for colonizing Mars?
If not, then why are there many people (except for space funs) talking about a near future (e.g. 50 year) colonization in a very serious way these days? Don't they realize this possible problem?