Well in my opinion , buying something that you considered as useless is not bad as you think especially if you really wanted to buy that certain stuff . We should only avoid too overspending , we have to make a plan or list of what we need for daily life and list of what we want to buy (vices is the good example), and separate a certain amount of money for the bill we have to pay .
I also don't find it bad to buy stuff that we want eventhough it is not that important as long as we have the capability to buy such stuff. Just make sure you are not overspending to the point that even your monthly food allowance will be spended. Knowing what to buy, how much to buy and when to buy is one of the key on good management ofyour money.