I don't feel like going to my friends wedding.
Why don't you want to go to your friend's wedding?
My friend is a stupid idiot who won't get a job and wastes his life shopping and playing video games
Unless you have a real reason not to go, like cost or other obligations, it is unkind to decline a friend's wedding invitation. They are likely only going to have one big wedding, and so you should be there to support your friend! Also, if they are really your friend, you shouldn't call them names and say that they're stupid.
Fuck them they are not my real friends.
It is hurtful to decline a wedding invitation to a friend. I think you should go if you have problems with how he lives his life you should tell him or mind your own business.