I'll respond to a few things:
It’s another to explain why you feel justified in spending your wealth upon houses and sculptures rather than helping some struggling people pay their rent
Spending wealth on houses and sculptures pays the rents of construction workers and sculptors. Every stupid/ludicrous thing that a rich person buys transfers that wealth to the employees of the company who created it.
And the super-rich, the infamous “millionaires and billionaires”, are constantly squandering resources that could be used to create wonderful and humane things
Money is like energy. It can't just disappear by squandering it. It is always transferred to others. (unless you burn it in a dumpster).
I'm not necessarily on either side of the argument, but let me pose some other questions that logically make this a slippery slope, and makes the issue posed by the article less black and white than the author would like it to be:
Is it immoral to take away another's wealth away by force?
Is it immoral to make poor financial decisions, knowing that it will inhibit your ability to help others?
Is it immoral to have kids, knowing that the expense of the childbirth could cure 100 kids of malaria?
Is it immoral to throw food in the trash, when there are people with no food that you could have given it to?
Is it immoral to eat all the food, instead of throwing it in the trash, when you could've eaten less and given the remainder to someone who didn't have any?
Is it immoral to only work 40 hours a week, when you could work 80 hours, in order to earn twice as much and help others?
Is it immoral for someone who is financially poor, but has free-time, to not spend all of that free time time volunteering to help others?
Is it immoral to avoid paying taxes, if the government collecting those taxes is inefficient with it's resources?
"But the central point I want to make here is that the moral duty becomes greater the more wealth you have."
Consider Jesus's parable of The Widow's Offering:
" Jesus sat down opposite the place where the offerings were put and watched the crowd putting their money into the temple treasury. Many rich people threw in large amounts. 42 But a poor widow came and put in two very small copper coins, worth only a few cents.
43 Calling his disciples to him, Jesus said, “Truly I tell you, this poor widow has put more into the treasury than all the others. 44 They all gave out of their wealth; but she, out of her poverty, put in everything—all she had to live on.”The author of the article thinks in terms of absolutes. If you can help 20 people, your moral obligation is greater than someone who can help 1.
Jesus, who I'd argue was a greater teacher of morals than the author (who conveniently avoided personal scrutiny, by posting anonymously), thinks in terms of percentages.
Every person is judged on what they did or didn't do, out of what they had.
Here's one example I like to give on absolutes vs. percentage morality:
Who is more immoral:
Hitler, an extremely hateful person with the desire to murder all jews, who was gifted with
legendary leadership and oratory skills, and was able to achieve those desires by leveraging the power and resources of an entire continent.
OR
Joe Skinhead, an extremely hateful person with the desire to murder all jews, who no one took seriously, and had no followers or access to resources to kill jews, despite his best attempts, and was outcast to the outskirts of skinhead society as a joke and a nobody, and therefore was not able to achieve those desires.
I think Jesus would argue they were
equally immoral.