A long way to go but I'm glad it's his mission
I think a prize system would work better. Make a prize for the first company or nation that could put a base on Mars that could comfortably support and maintain 100 humans. If Musk and others could put $5B into a prize fund, open to the entire world, and let it grow in 20 years it will double or triple in size, making it a sure thing it will happen eventually.