Stories about CTOs heavily overrelying on their long-outdated coding experience are plenty. If that's an ego thing ("I can still do that and show them that I can"), they're going to do that with little care about the consequences.
At that level, it's the combination of all the power and not that much tech expertise anymore. A vulnerable place.
A lot of famous hacks targeted humans as a primary weak point (gullibility, incompetence, naivety, greed, curiosity, take your pick), and technology only as a secondary follow-up.
An example: Someone had to pick up that "dropped" pendrive in a cantina and plug it into their computer in a 100% isolated site to enable Stuxnet.
Were I a black hat hacker, targeting CTOs' egos would be high on my priority list.