There are inexpensive ways to ground your boat. A very, very accomplished sailor-friend of mine grew up in the islands. In all honesty, they would wrap the
anchor chain around the shrouds and let it drape just off the boat.
Thus, if you are really that worried about it, you can just do that. Is it worth it... well, that is a question we each must answer...
I have read about the dissipators and the science seems logical. Of course, I am a biochemist, not a physicist. However, it is not 100%. When I said earlier that you keep your boat from being hit so it hits your buddies boat... well, that is not far from the truth. And the trick about lightning, as MANY OF US HAVE SEEN: IT DOES NOT HAVE TO HIT YOUR BOAT. If it hits anywhere close to you, you can kiss your electronics goodbye. Thus, here is a good reason to: ALWAYS CARRY
HANDHELD BACKUPS. They are not that expensive, and might just save your life.