A few comments:
"If the most successful people are becoming more effective and the least successful remain consistently ineffectual then you get a divergence in wealth. If the baseline is zero and the top line goes up then the two of them diverge."
The author's mistake here is to assume "being more effective" has any real bearing on who is the most successful; random chance providing a substantial push in the right direction and then post-facto narratives denying chance are far more likely. Environmental factors increase exposure to upside of chance while minimizing the downside risk. Therefore, rich white people are typically thought of as the "most successful" people because they were born to a similar demographic which ensured they would land in an okay spot.
"Is it really such an issue if a few people get rich so a lot of people can wealthy?"
The "lot of people" aren't get wealthy. Most people are getting less wealthy while the very richest are getting substantially more wealthy. By and large, nobody is "getting rich" so much as "getting richer". As someone else said, "a rising tide lifts all boats, but most people can't afford a boat, so they drown."
"I’ve never met a wealthy person that hates the poor but I’m shocked by the number of poor(er) people I know who hate the wealthy. I never really understand why since they’ve never obviously suffered at the rich’s hands. But then it something doesn’t have to be obviously bad to add up. It just has to be occasional, careless or callous and over time it accumulates."
Ah, an out-of-touch comment by a rich man; the poor "hate" the rich because they frequently seem as though they are from a different and better planet, and they really think that it would be much better if all the poors could just move to that planet gracefully, like they did. After all, "I did it so anyone can do it." Completely and self-servingly ignoring the reality of wildly different starting conditions while subtly implying that their final superiority is some sort of inherent Aryan guarantee.
Additionally, the poor do obviously suffer at the rich's hands, though perhaps they don't see it this way: bank overdraft charges, paychecks on prepaid cards, more scrutiny and arrests for trivial offenses from law enforcement, increasing rents, outrageously expensive and ineffective health insurance, etc.
Anyways, just to put this topic directly to bed, the wealth gap is actually bad, and the lack of empathy that the rich have for the poor is a historical fact rather than an issue itself. The IMF is against wealth inequality and has detailed how and why in depth: https://www.imf.org/external/pubs/ft/sdn/2015/sdn1513.pdf and to be blunt, they know better than any of us here. The bottom line is that, as the report says, "Societies with greater income inequality experience slower and less stable economic growth." Even the capitalists have to get on board with solving the problem of inequality when it's framed that way.