In the 2040s. The upcoming wave of robotics will push the cost of goods down enormously low, robotics + need for compute + cheap goods will cause a huge increase in demand for raw resources; mining on earth will not be able to keep pace & environmentalists will get generally upset about environmental destruction caused by resource extraction.

People's attention will shift to obtaining resources from outer space, which leads to more demand for space exploration, and then space manufacturing to avoid polluting earth. Then the general sentiment towards a lunar/Mars colony will trend towards positive, and people will desire to run away from political problems on Earth. So significant investment towards building a Mars colony will happen then.

The technical problems with a Mars colony are not insurmountable, it's completely possible to build a colony with 2026 technology, just the cost is too high. Better technology (robots) and innovations (i.e. upgraded Starship) will push the cost down.