You are right. The real motive for that attack is unclear. I know a few years back some Chinese guy attacked a kindergarten, and I would say the wealth disparity problem was the motive for that.
As poor men in China are just ignored ( generally speaking ) by women, it must generate a lot of frustration and anger, even rage among many working class Chinese men. For them, the future is no wife ever, no love, no sex ( unless they can find cheap hookers )

So, in contrast to people saying I am a "China hater", I do have sympathy for those guys. To but it bluntly, Chinese women have ridiculous and unrealistic expectations of men.

This is a big, big problem. For one, it results in schools putting far too much pressure upon students, saying that if they get no university education, they'll never get a wife etc.

A sad thing is that the honest guys that never cheat anybody, are more likely to end up dying lonely that those that make loads of money by bending the rules at every possible opportunity. The government has already recognised this problem (the wider issue of corruption) as threat to social stability and the legitimacy of the party.