I hate this unfair and selfish behaviour

My brother in law is so selfish that my bf and I need to share a single bed on a bedroom shared with his other brother, while he has his own room and double bed... (we are staying at their parent's house for the summer). It bothers me a lot bcus I don't see how we need to be uncomfortable af for him to be like a king... when he is the last one to put any input towards anything - we are the only ones here to pay for food and help with bills! Also how can their parents pay for his course, driving license, rent, all bills and give him a monthly amount of money to survive? While my bf has asked for a loan to live off and pay for education instead - and they refused to help pay for his DL. I hate this so much