All systems tend to collapse, it is the order of nature after all. Greed is but a side effect of a collapsing system, one where ethics, i.e. rules and regulations are lax and the optimizations are focused on variables that are sometimes unimportant to the larger picture. This is not only because we as humans can't agree on infallible laws, but because the agreements themselves have an expiry period while the laws might not.
Some of society's biggest mistakes have been in holding onto traditions and constructs that have affected it's ability to accept the realities of the times. What gibberish? Well, that is exactly what we see on a day to day, in how the herd tends to treat the "pioneers"/"witches". More than enough times, the innovators and radicals have given more to human progress and quality of life than what a few bad actors could have taken away.
Take some time to understand these points and you will notice that quite often the answer to solving for greed is only in using it to our own advantage, i.e. only the greediest tend to win, by using the greed of others to compound their own gains. Greed is not wrong, it is part of the lived human experience, a survival instinct none the less. The challenge we face when building policy that truly accounts for greed is in tackling the optimizations that may override the checks and balances we can come up with, factors that just can not be foretold.
This is exactly why all rules and regulations must be dynamic, applicable at well defined levels and jurisdictions. But that again brings forth challenges in implementation, in it's true effectiveness and how it could just end up affecting the quality of life we were vying to improve.
What do I think is the right solution? Simpler laws, more dynamic regulations, regulatory bodies with the right level of authority and true democratic participation at all levels of the process. Which means we need more local self government with better incentives for all to participate in, equally.