Harming others in a direct way is a lot more obvious than harming others in indirect ways, such as greed, manipulation, psychological abuse, etc. It's a lot easier to justify "invisible" indirect harm, be it individual or collective because both short-term and long-term impact only is observable when it's super obvious (e.g. affecting entire nations or large groups within society).

But the problem manifests way earlier and at those stages, it's considered ok because most people just don't make the connection. They don't see and don't feel how they are experiencing the negative consequences of the system, so they keep supporting it.

Another aspect is that people who are worse off hope to become filthy rich at some point and join the club, with all the beneficial aspects (on an individual, selfish level) and all the detrimental aspects (on a collective, socially destructive level). This is usually justified by an "I had a shitty life, so it's my turn to return the favor" attitude (oversimplified).

Obviously many other factors that play into this as well.

My point being that there is a general reluctance among the population to tax the (ultra) rich properly and fairly, because they don't see how it's a problem because they don't experience the side-effects (yet) and because they also want to profit from this system before it's no longer possible.

I'm also not sure if greed is 100% human nature; specifically excessive greed seems to be linked to other factors. People can grow up very humble and continue to be that way all their life, despite having plenty of opportunities to be greedy. So I believe there is more to it.

Maybe the system in place is the biggest issue here, it's difficult to tell. What I do observe is that greedy behaviour is rewarded all the time, so it's basically encouraging selfish (in)actions. And maybe once you discover how to navigate life efficiently and successfully by being greedy, you won't stop because you realize how it trivializes so many issues.

If you think about it, being (ultra) rich is literally winning life. Death is basically the only limitation, but other than that you can do whatever you want whenever you want. Everything that is a big problem for regular people turns into an invoice. If money can't solve your problem directly, you hire someone who will solve it for you one way or the other.

So to provide a different perspective, maybe (ultra) rich are not addicted to money or greedy per se, but rather unwilling to part from its potential as an instant problem solving currency, as well as a social lubricant to incentivize people to do what you want.

I think there are very few people who would step away from several billions, after experiencing that kind of life for a few months. And once you have the mindset of money as a problem solver, you will probably imagine millions of scenarios why you need more.

So maybe taxation isn't enough, and maybe small systemic change also isn't enough. Maybe we need to overthink our approach as a species and tackle all the existing issues. Because if there are no problems that can be solved with money, money might not be considered a top priority.