But i would rather to sail across the ocean than to ride a motorcycle across the United States. Sailing is safer than riding a bike.
You are obviously speaking for yourself. Riding a motorcycle across the US is not
more dangerous than sailing across an ocean if
you are more skilled as a motorcyclist than a sailor. I assure you, my four motorcycle trips across the US were far easier and less perilous than any ocean crossing. Maybe it's because I'm a seasoned motorcyclist and have developed the confidence and skill required for the task.
When I discovered motorcycling I was scared, had frequent dreams of death on the bike (like 2/3 nights a week for the first 2 years of riding.) I just enjoyed motorcycling too much to give it up so I decided to take that energy from the dreams and start researching motorcycle safety. I read everything I could find about motorcycle safety practices from professionals like motorcycle policemen, couriers and racers. I read all the magazines (no interweb back then) and all the books I could find about motorcycling. Now, 35 years later, I can look back on thousands of fond memories of trips made, people met, roads enjoyed and an appreciation of our great country, coast to coast.
It's not a question of is it dangerous, of course it is, just like sailing. The danger decreases with knowledge and experience but it's always there.