Every single time a developer releases a piece of code not covered by tests, he/she is basically taking a bet, hoping that things will work. And very often that

Every single time a developer releases a piece of code not covered by tests, he/she is basically taking a bet, hoping that things will work. And very often that is simply not the case. Releasing not tested code is simply unprofessional and wrong in so many different ways. I honestly don't see any valid argument to not write tests.