The wealthiest people in the U.S. have their money tied up in assets, including real estate, stocks, trusts, precious metals, etc. You aren't going to be able to tax more than their income, which is a small fraction of their wealth. If you want to raise their income tax by some percentage, go ahead, but it's not going to transform the economy anything like Bernie Sanders and Elizabeth Warren are saying--e.g., pay for everyone's healthcare, pay for everyone's education, etc. It would have to be middle-class incomes that are taxed to provide those things, which is why it will probably never happen.
Healthcare for all inevitably means that people who work and earn a certain income are leaned on to buy healthcare for people who do not. There's no way around this, regardless of how you present the costs as premiums, deductibles or taxes. This already happens with medicare and programs for people on welfare. Obamacare, which is still in place, expanded this and it pissed a lot of people off when their monthly premiums doubled for the same quality of service. It's one of the issues that got Trump elected and will probably get him re-elected. If you can get pharmaceutical companies to lower their drug costs, go do it, but it's more likely to be a free market economy that achieves this through fair competition.
The U.S. population has expanded dramatically and the economy has transformed dramatically over the past 40+ years. The companies that earn the big money are largely technology and information-based businesses with extreme scalability and efficiency. Andrew Yang is correct when he says that improvements in business efficiency, including the ability to use automation, are displacing workers and adding to income inequality.
Criticize people like Jeff Bezos if you want, but he has also created more jobs for people, including high-paying jobs, than 99.99% of people. His businesses operate with greater precision and efficiency than anything the U.S. government could plan and execute. And if his employees don't want to work there, they can work somewhere else that treats them better and pays more. That's how a free-market economy works. Even Democrats understand this.