They both cause a lot of trouble in the ocean? It's unhealthy to be hit on the head with either one? I'd do my best to whack either one away from me with a golf club? All true. But also, they both have surfaces designed to take advantage of physics.
Oh, there are so many reasons that sharks are like golf balls. They're both tough to film, but they both get an disproportional amount of time on television, and both are so much more fun to watch if, somehow, there is blood involved. The connections go on and on. But only one connection has to do with physics.
Golf balls, if you've noticed, have dimpled outsides. This allows them to fly faster. A smooth ball clears a path through the air, leaving a clear, wide wake of low-pressure air behind it. This low pressure air sucks the golf ball backwards, slowing it down. The little divots in golf balls create pockets of turbulence that cause air to swirl around the ball. They hug the back curve of it, pressing close and creating a smaller wake. This smaller wake does less to hold the ball back and lets it fly farther.