Since I'm a freelace writer (visit website for more), I have travelled a great deal alone, and the advantages are clear. So are the disadvantages. It is harder for a single traveller to get rid of predators of one kind or another (not all locals are genuinely "friendly", and nor are other travellers) or even just bores. Illness is not always something that can be got over in a day, being robbed happens despite best precautions (and not always in places with reliable or even safe law enforcement) and people travelling together can help each other / get help in truly difficult situations. Travelling alone in a safe environment (good transportation, optional tours, etc.) is fine, but I cannot endorse advice to inexperienced "adventurers" to attempt dangerous trips or destinations alone. A particular place or activity is most often considered dangerous for a reason, and while "I was OK, you'll be OK" stories are frequently heard, try not to be too naive or to overestimate the importance to your life and self-esteem of just doing whatever you feel like in the moment, when you may be putting yourself at a very serious disadvantage.