Never been a proponent of building a colony on Mars, or the Moon. Both are exposed to far too much solar radiation to ever be habitable. However, building safe habitable environs INSIDE Mars or the Moon is possible. TBM’s (Tunnel boring machines) could create massive deep chambered pressurized spaces that could accommodate millions of people. Massive solar farms could be built on the surface for energy for underground hydroponic farms, with pocket nuclear reactors for back up."But living on Mars? No way; The environment is too deleterious to life, the support life line is too costly and too tenuous."
I totally agree. Limited colonisation may be theoretically possible. Difficult, expensive, non-viable, but theoretically possible. Terraforming. Absolutely no way.