In many cases, not all, that the game is rigged for the wealthy and rigged against the common man, or those who feel left behind. Both Trump and Bernie's messages appeal to different parts of this group, and IMO is the main popularity of both of these " stick it to the establishment" candidates.

What can be done to keep capitalism, yet put some limits on it's excesses? Unions, in principle, were great ideas when they were needed in that they provided workers with good pay, healthcare, and pension. However, they became too difficult to work with given their bargained for rules, etc that operationally. Good companies that have good union relationships are not failing. And of course that's just a small sliver of the problem. Growing healthcare cost becoming a large part of family budgets which disproportionately impact lower wage families(is another piece of the puzzle) and people's view of coddled do nothing Congress reps who are not solving these problems.