Manufacturing fuel in orbit requires sending the plant in orbit, extracting the raw materials, packaging them then bringing them up there and also involves send

Manufacturing fuel in orbit requires sending the plant in orbit, extracting the raw materials, packaging them then bringing them up there and also involves sending a ship every time a maintenance is needed, unlike Mars where the raw material (water, CO2) are already nearby. ISRU (in situ resource utilization) is the best way to go, i.e. you bring the plant to Mars but at least you use the local raw materials.