So he’s effectively moved in whist making zero financial and domestic contributions. Congratulations, you’ve bagged yourself a Cocklodger.
You need to stop asking why he is like this (psst, it really isn’t that complicated, he’s lazy, selfish and entitled) and start examining why you don’t value yourself more. If you did value yourself, he would be contributing because you would have told, not asked, him to.
Work out what his contribution should be and tell (don’t ask) him to pay it by standing order. If he refuses, complains or tries to negotiate tell him you are done. May I suggest you have ‘Bills, bills, bills’ by Destiny’s Child playing in the background to keep you on track.
You triflin', good-for-nothing type of brother
Silly me, why haven't I found another?
A baller, when times get hard
I need someone to help me out
Instead of a scrub like you, who don't know what a man's about
Can you pay my bills?
Can you pay my telephone bills?
Do you pay my automo' bills?
If you did then maybe we could chill
I don't think you do
So, you and me are through.
You are young, you are not his parent, so stop acting like it.
The good news is, you are young and hopefully this shit has been a wake up call.