So, Elon decided to take a capitalist way and to do every of his tech in dual use (I mean space, not military): - Starlink aiming for $30 bln/year revenue in 2030 to build Starships for Mars at scale (each Starship is a few billion $ and he said needs hundred of them), - The Boring company (under earth living due to Mars radiation, - Tesla bots, - Hyperloop (failed here on Earth to sustain vacuum but will be fine on Mars with 100x smaller athmosphere pressure) etc.
Alternative approaches are also not via taxes and government money but like Bezos invested $1 bln/year last decade into Blue Origin or plays of Larry Page or Yuri Milner for Alpha Centauri etc.