What the article says is that upper middle class feel that their potential income earned is stagnating RELATIVE to the super rich whose income is still increasing.
The middle and poor classes are already beaten into a silence that their standard of living will always remain stagnant and they will not enjoy the advances in the economy (since around 40 years ago).
It corroborates your point about why rich (in my definition, upper middle class) people would be against the idea of UBI. A lawyer making around 200-300k/yr has had his wages increasing around 5 times slower than a CEO / ibanker making around $2m a year. Instead of thinking, "hey I have a ton of money that poorer people could really use right now", they are instead thinking, "hey, how come THOSE rich people are growing their money soo much faster and I still have to slave away for 20 years before I can pay off my house?"
The term "rich" isn't good enough as a classification nowadays because there's a huge difference between the top 400 individuals in the US, the top 1%, and the top 25%, and they're all considered rich by the old definition.
I mean, I can understand why rich people would be against this idea. The whole thing about being rich is that you can take a few dollars from everybody and get rich. But the reverse could be quite painful. Take a whole whack of dollars and give a few dollars to everybody. It appears to break the "get rich" thing... Until you realise that poor people will spend that money (i.e. give it back to the rich people). Ford hired private investigators to make sure the people he was paying minimum wage to were going to spend it. Ford was a smart guy (Nice guy?? No idea, but definitely smart).
I really think that if you want fly the idea of rich people funding the improvement of society, you need to link it back to them getting richer. Otherwise, without a revolution, I don't think you're going to get anywhere. They can spend quite a few dollars lobbying government before they get anywhere close to spending what they would need to spend to improve society.