Making Humans a Multiplanetary Species (2016) https://www.youtube.com/watch?v=H7Uyfqi_TE8

Elon Musk talks Climate Change and Carbon Tax at the Sorbone 2015 https://youtu.be/sUFwwlmxRsw?t=978

It could be that he was just following the trends knowing there was money to be made, but I detect some real passion back in these videos.

Of course no motivation comes from a single source and there's some mix of philanthropy and money driving this, among other motivations.

Either way his tone has changed a lot, to say the least.