unsecured debt is a scary thought

Student loans cannot be discharged in bankruptcy. They can default but the government will collect via garnishing unless the student makes literally zero legal income the rest of his or her life. Student loans are extremely secure.

the rich who properly invest will earn compounding returns

This is absolutely NOT the reason the top 1% of income earners are capturing 99% of new income. Billionaires don't buy billions of dollars of S&P 500 ETFs and make their money the same way middle class Americans do.

college costs have exploded over the last few decades

Colleges are expensive because federal student loans are so abundant. They charge a lot because they know they can. If they became federally funded instead, this wouldn't be an issue.

Increasing earnings quarter after quarter drive so many business decisions that any dip, even one due to taxes, could spell disaster for employees and our retirements.

I really have no idea what you're saying here. Companies have dips all the time and you don't see it causing massive layouts and affecting anyone's retirements. Do you think most people still have pensions with their employer these days or something?

I do feel he seems to lack an understanding of dynamic systems and how truly global the economy is

This seems like a really ignorant thing to claim about someone who's likely been a politician longer than you've been alive. He's been on committees for budgets and health, education, labor, and pensions and probably understands these "dynamic systems" better than most anyone else.

I really have no idea how you can claim you have a better understanding of these things you only casually read about than Bernie Sanders - someone whose entire life and career, spanning many decades, is intimately involved in all of these subjects. Can you see how some people would view that has horrifically ignorant?