because if everyone has their best interests then they will do everything to benefit themselves. although this will lead to a lot of selfishness more people would do less bad if all they cared about was protecting themselves. such as if they thought they could go to jail if they robbed a bank they wouldn't because it would be against their interest/ it could negatively affect them. but a majority of countries already have a punishment policy in place for bad behavior. ie: laws yet people break them knowing the consiqunces, some people might make the argument that they break the law because they don't have their own best interest which in many cases is true. I hope this helped I tried to give you views from both spectrums so you can make your own answer why Smith supports this claim. don't forget to rate and thanks me it helps loads. have a good one.
