When I looked at this, the first thing which popped into my mind came from the 95th percentile graph... third one I think.

If you're a CTO, CEO, CxO, you have direct, in depth knowledge to how the company is doing. You also likely have insight into how that translates into free capital to spend on wages. Many companies are not public, and even when companies are, earning reports aren't easy for a line worker to fully understand.

So if you have that knowledge, it's much easier to push back when someone says a wage increase isn't possible. Such as the board, or the CEO (eg, if CTO, or whatever).

This by no means "makes it fair", it's simply that the inequality may be from knowledge, and therefore bargaining power.

Another aspect of things, is that every CxO class worker can agree, their knowledge is very very important, irreplaceable in fact! Upper management, you see, is quite valuable, as of course (from their perspective) "I'm irreplaceable and valuable!". Who doesn't think they have value, after all?

But.. those line workers, or even those engineers, well.. they're like cogs. One as another.

Some might attribute malice to the above thoughts by CxO class individuals, but it can also simply be driven by self-belief in innate value, and by good old ego.