Two wheels require balancing, like that analogy of walking with two legs or four. The rider needs to have equilibrium and this aspect must be learned, sometimes in an early age. A car has benefits and disadvantages, as everything. But in terms of pollution, a motorbike doesn't need to move as many kilograms, consuming less gasoline in the same distance.
Another great advantage of motorbikes is the ability to pass through places where a car can't. Very rare cases of the contrary situation, singularly roads near cities. A tunnel with fire could be very dramatic for four wheel vehicles, right? Some traffic situations do not allow the normal flow of vehicles and the person could be more or less trapped inside it.
That's not the case with motorbikes!
There are however multiple disadvantages like the need for better protection, in multiple aspects. Meteorologic conditions and also for eventual accidents. That's why a motorbike rider should be much more careful, moderating speed and then increasing security via reaction times, avoiding the severity of a possible accident. Using special clothes with protections, and an extra care, allow an optimistic view of the future riding a motorbike.