The problem of climate change is only getting worse. Steyer's strength is that he has always put this at the centre of his political career and agenda.
Steyer has long been a climate activist. His super PAC, NextGen America, has put millions of dollars towards fighting climate change and making it a major part of Democrat's political agenda. He has also expressed support for the Green New Deal. Steyer has campaigned both for Democrat candidates across the country and to impeach Trump. He spent millions of dollars of his own money on a series of TV ads in 2018 calling for Trump's impeachment, despite the Democratic party requesting he stop the ads and calling impeachment "unrealistic". He helped to put impeachment firmly on the agenda, and stuck to his convictions. Steyer has the combination of personal conviction and support for strong policies that is crucial for a Democratic candidate.
Steyer's convictions are not as strong as they may first appear. Steyer's investment firm, Farallon Capital, invested in fossil fuels, suggesting that these strong personal beliefs may be suspended for personal gain. Most importantly, strong convictions do not make a Democratic candidate. The money he has donated does not speak to the personal qualities needed to translate these convictions to concrete change in the role of President. The money he is spending on his Presidential campaign would be better spent elsewhere.
[P1] Steyer has donated large amounts of money to causes important to the Democratic agenda. [P2] These strong personal convictions point towards strong character as a leader representing Democratic values.
Rejecting the premises
[Rejecting P2] Many people have strong personal convictions - this does not correlate with their aptitude at becoming President.