Other than, “Because we can” there is no reason to send people to Mars. Maybe after a few centuries after we terraform the place.
May not be possible due to lack of magnetic field, which protects our planet from the solar winds. Dwellings would likely have to be enclosed in protective bubbles.
True terraforming consists of creating and retaining an atmosphere with sufficient oxygen to sustain Earthly life, a lack of harmful amounts of other atmospheric gases (Mars' atmosphere is predominantly CO2) and a hydrologic cycle (That's water to you folks in Rio Linda). Earth's magnetic field prevents the oxygen and water from cooking off into space, as apparently happened on Mars.