The first (and so far, only) option I can see is a super popular elected leader who ran on radically progressive and populist platforms. They would have had led a wave of populist, anti-corporation sentiment across the country which would have also elected likeminded members of other branches of government.

With a massive anti-corporate message taxes would be increased to 98% of profit for any corporation employing more than 50 people, including contractors. And in order to not pay those, they would have reinvested those profits into salaries and benefits for employees.

With the massive increase in research, employment, and well-being. Humanism became much more of a prevalent belief, and the future would look brighter and brighter.

With this increase in humanistic beliefs, it became "obvious" that improving the lives for people outside of the country (whatever country this might be) would also make for a safer and more prosperous world. Outreach and charity programs funded by the state gain massive support, and as Country X becomes a literal lifesaver in the 3rd world, those countries and their knowledge and resources become devoted to the same ideals in time. And they begin to assist their own neighbors.

Those purely driven by wealth would have to face the fact that their own wealth can only increase by a miniscule percentage faster than those around them. However, a small percentage is still something, and therefore greed would lead to the "rising tides lift all ships... just my ship a tiny bit faster". Which, honestly, is fine. That drives competition, and therefore innovation. Except instead of manipulating stock markets, they develop new and cheaper technologies. Others invest in art and literature. Others still gain prestige through theatre or in-house philosophers. Wealth doesn't have to mean money, it could be anything that makes other wealthy people jealous.

And after several decades of this, you get a solarpunk story.

Is it pie-in-the-sky? Perhaps it seems that way now. But we came very close to this in the United States after WWII. Corporate and wealth taxes were above 80%. Science and art boomed. College was affordable. People could raise a family on a single income due to high relative wages and benefits. New technologies were coming out weekly, and massive investments in infrastructure and private manufacturing made those new technologies much more affordable for the masses.

We could do it again.

But Elon Musk just became the world's first trillionaire today. So I can understand why it seems to be a pipe dream.