One of the biggest changes needed to be made to preserve our planet is the excess of wealth.

Scientists are warning that human economic activity has overshot most of the planetary boundaries.
Many scientists say degrowth is necessary for Earth's survival long term. Degrowth argues that to save Earth, humans need to reduce global economic activity. This is because at our current levels of consumption, the world won’t hit the IPCC target of stabilizing global temperatures at no more than 1.5 degrees of warming.

Some Statistics that Promote Degrowth:

-Carbon dioxide is the main gas that causes global warming. The richest 10% of the world’s population is responsible for more than half the world’s total carbon emissions since 1990.
-An individual in the richest 1% emits 100 times more than an individual in  poorest half of the human population.  
It’s not only that rich people consume more things than others, but also because the things they consume are more energy-intensive. Large houses, cars, private jets, and luxury imports for example.
-In the United States the richest 1% have nearly 40% of the nation’s wealth. The bottom 50%, by contrast, have almost nothing: only 0.4%. On a global level, it’s worse still: the richest 1% own around half of all the wealth in the world.

The richest 1% alone capture $19 trillion in income every year,  which represents nearly a quarter of global GDP. That adds up to more than the GDP of 169 countries combined – a list that includes Norway, Sweden, Switzerland, Argentina, all of the Middle East and the entire continent of Africa.

If we want to live on a safe and habitable planet, we need to do something about wealth inequality.

One approach would be to introduce a cap on wage ratios or  a "maximum wage policy". Sam Pizzigati, an associate of the Institute for Policy Studies, argues we should cap the after-tax wage ratio at 10 to one. A 2017 poll found that a majority of the British public are in favour of a maximum wage policy like this one.

Another way to solve this problem is with a wealth tax. The economists Emmanuel Saez and Gabriel Zucman have proposed a 10% annual marginal tax on wealth holdings over $1 billion.  This would push the richest to sell some of their assets, thus distributing wealth more fairly and cutting rent-seeking behavior.
(The Correspondent) (Vox)