The coconuts that fall are usually mature and mostly dried out and don't nearly weigh as much as a fresh coconut. You'd still get injured not not likely to kill you.

I was also less worried about a coconut falling on my head because they would get harvested (by climbing the tree and felling them) before they turned mature enough to fall on their own.

Someone said they fall in a bunch. They might, but it's very rare. I've never seen coconuts falling in bunches unless they're being fell.

I would be more worried about the coconut leaf falling on my head. Those things are damn heavy and do tend to fall randomly and frequently, albeit with a large enough noise that you can run away to save your head. They made excellent fuel for cooking though.