Ask HN: Are CIO/CTO roles more vulnerable than other C-Suite roles?

Specifically, I want to ask the following:

1. Are CIO/CTOs more easily replacable than other C-Suite execs? - maybe because there's more talent competing here than other C-Suite roles.

2. Do CIO/CTOs have shorter career spans? - maybe because keeping pace with technology is much harder (compared to other business functions) and if you're left behind, you're no longer relevant. I understand that this role is part technology and part business/leadership, but keeping pace with technology and competing with new generation tech leaders (vs leaders in other business functions) is much harder.

3. How do C-Suite execs / board view the CIO/CTO role?

4. On average, do CIO/CTOs make less than other C-Suite execs?