If you work at FAANGMA and you received a generous 4 year on-hire RSU

If you work at FAANGMA and you received a generous 4 year on-hire RSU and you are still in your role, why? I have been running projections and it seems to make no sense to stay after 4 years. I've taken into consideration: annual base bumps, RSU grants and bonus.

Is it that you a) joined at fairly high comp, b) are comfortable with the comp you now make, c) other?