The chance of getting hit by lightening is remote. In open water without any other high structures around the risk is probably higher, but 5 or 10X a remote risk is still an event that is unlikely to happen.
5 lotto tickets gives you a 5x higher chance of winning, but you would be a fool to quit your job on the strength of this increased chance.
I have been struck by lightening, but at anchor. This make sense, because I spend much more time at anchor than in open water.
The closest I have come in open water was a bolt that hit about 50 yards away. I was at the helm at the time and shouted down something like "God that hit the water only 50 yards away" (There may have been a couple rude words that I have edited out)
A friend who was a guest at the time (sheltering down below) said "Thatís good It sounded closer than that"