He is degrowth in ways that suit his selfish preferences (contracts for his companies over better alternatives, and wanting to avoid any proximity to other Americans in public).
edit due to rate limiting: Yes Musk is one of the reasons we don't have high speed rail in California at least. He admitted to creating Hyperloop as a fake and hopeless project simply as a campaign to get high speed rail canceled. And he used DOGE against it to further cripple the project. He used government authority to contribute to regulations against mass transit. His projects are literally fake psyops that don't deliver transit and exist to spoil mass transit options from growing.
We had mass transit before he got rich. Are you opposed to it because it's not perfect so we shouldn't do it at all instead of doing more of it? I don't understand the degrowth attitude of preferring luxury options that scale worse.