Wealth is power. Power matters, as with it you're in a position to decide what can be consumed to begin with. People that control wealth control what policies get implemented, which projects get funded, etc. They will not support policies that reduce consumption because it would reduce their income and power. They will support projects that waste resources if it makes them more money and power.
Consumers also don't support policies that reduce consumption because that would reduce their quality of life. Consumers happily take flights, hot showers, run their AC, etc. if it makes their lives easier.
A billionaire consumes less of their income and invests more than a regular person. Wealth is power, but virtually everyone would spend on the same things.
Making a choice to consume as an individual is different from supporting a policy that would affect everyone. Taxing consumption and fossil fuels does have a lot of support. People are willing to reduce their quality of life if everyone else does as well, but their not willing to make the choice not to consume as an individual if everyone else can continue to do so.
A billionaire has the power to affect policy in a way that the average consumer doesn't, and is more likely to use that influence to make themselves richer than to push policies that benefit everyone.
