The idea is that the market (i.e. excluding the market makers) is usually long protection, therefore writing options usually is a profitable business. By selling the tails you can make income as there is more demand for buying options than selling them.
The problem is that if it hits the tails you may be liable for large amounts. Normally overally if you do not write large amounts of it and hedge a bit with more liquid options when it goes against you, you should be making money …
See it as an insurance against large losses and it will all make sense.