A bolt of lightning isn't just a danger to the spot it strikes.
A lightning bolt contains an enormous amount of charge, which is delivered to a single point on the ground. Now, since like charges repel, all of that electric charge wants to spread out (which is why it flashed down from the sky to begin with). That charge wants to spread out in the directions indicated by the arrows, but the ground has a very high electrical resistance - much higher than that of the human body. If your feet happen to be standing on different equipotential lines (the concentric rings), then there is a (large) voltage difference between them, which pushes an electrical current through your body as the charge from the lightning bolt attempts to separate. If you're standing, the current runs up one leg, through your pelvis, and down through the other leg - this is survivable. If you happen to be lying down, the current runs through your heart and brain, which is typically fatal.
Lightning also carries an enormous amount of energy. In the early 1900s, it was calculated that a single bolt of lightning contained enough electricity to power the city of Chicago for a month. Obviously, a bolt of lightning would not power today's Chicago for that length of time, but it does give a sense of scale. Harvesting this energy is an electrical engineer's wet dream, as it's free electricity just flying around in the sky, and there's a lot of it. I digress. Let's look at a few other secondary characteristics of lightning. This is called an arc flash:
Two things happened in that video - an arc flash and an arc blast. The flash refers to the build-up and dissipation of heat energy, while the blast refers to the sound and pressure generated. The blast alone can kill a person. Arc flashes are so dangerous that electricians working on industrial circuit boxes are sent into the room in what is essentially NATO body armor.
It is important to point out that an arc flash is just a lightning bolt's baby brother. Rather than being localized inside a metal box (which often explodes in a spectacular fashion), a bolt of lightning is superheating a few miles of air. That air pushes apart because it becomes electrically charged, then bangs together to close the vacuum. That air smacks together so hard you can hear it from miles away. You know how loud thunder is? Imagine standing six feet away from it. The intensity of sound when you're that close is so great that it can physically harm you.
Now, consider the tertiary effects. People who electrocute themselves generally aren't harmed by the shock. Instead, their muscles spasm and throw them off a ladder. You're in a room where everyone has just been electrocuted. Thunder has shattered windows, and there's broken glass lying all over the place. Electrical currents are causing involuntary body movements. People are falling over, knocking things down, and what have you. The electric shock you experience may not seriously injure you, but when your girlfriend falls down the stairs and takes you with her, you have a problem.