Keep in mind that the wealth inequality in historical norms is spectacularly low. Yes, it was lower for a while due to WWI and, especially, WWII. The situation, in relative terms, is still much better (20-30% more equal compared to the beginning of the 20th century, hundreds of percents compared to before) for the poor than it ever was before. In absolute terms the situation for the poor is so much better it's not funny.

Not saying we can't do better, but we're actually not doing all that bad at all. Of course, it's moving in the wrong direction.

I disagree with the government regulation thing. It's true, yet it's so wrong as to mislead. The government did institute draconian regulation on businesses which lead to decades of limited profits or even losses, but it did so because of the wars. So the government is responsible for inequality reduction in the same way that an engine is responsible for a car's acceleration. The decision for the acceleration was made by the driver, and the driver for these policies was war. Without a doubt, no sane person, poor or rich, wants a return of these policies, no matter how much they'll reduce inequality.

I think you'd have trouble arguing that US involvement in WWII wasn't dictated by government regulation (Lend-Lease and the Japanese Oil Embargo), but the point was more that it's not an irreversible trend.

Presumably if there's some optimal wealth inequality based on our technology level/social structure/ect. we'll naturally trend towards it on a long enough timeline.