Maybe they try to protect themselves from the real problem. It is easier to be mad at you than to acknowledge something that might shatter their world.

I can say Hi, and every one is "what's with the attitude?? " I'm sorry, but there's no winning.

Maybe you ought to steal some of your brother's drugs, and then you can relax and gain a better "tone."

Classic enablers.

Lock your room. Save. Move out. Win for yourself, not them.

They're gonna end up with him worse off or dead if they keep that up.

A lot of parents that have children with addictions or risk taking behavior become overly strict towards the other child(even) in the house in an unhealthy attempt to feel like they have control. It's "safer" to yell at a largely rule-abiding child than once that displays erratic behavior and has no morals, ethics, or respect for their parents. Unfortunately, chances are that they will never outgrow their selective punishing and that you will be better off saving up to move out. If you can a bank account or lockbox to put your money in, in order to keep your brother out of it, do that. Ask if there's a way to prevent your parents from accessing it, and if there is, do that too.

I am sorry to burst your bubble, but while the stealing is a major problem for sure, the tone is also a problem, and it is not serving your purposes. The tone changes the message. We humans only rely on the actual dictionary meaning of words for only 7% of the message; the rest is the tone and body language. A poor tone can change your message from, for example, "I have this problem of having my money stolen and would like your help and collaboration because it does not work for me; it makes me very upset" to a judgmental one, of, for example "I think you are incompetent and are irresponsible, and are bad at your skills of parenting, and I look down on you". The former can hopefully elicit a collaborative finding of a solution, and the latter can make the listeners feel threatened, defensive, and uncooperative. This sample difference in the message received can often be about HOW one speaks as opposed to WHAT one says/is trying to say. Try talking to them calmly, when you are calm. And express what you are feeling in kinder words, and get them to see your issue.

Seems to be a common thing with us firstborn's. My youngest sister is 21 still lives with our parents. When I turned 18 I had to move out ASAP. I am the only one of their kids married and with a successful career yet I'm treated as a failure.

They probably know and are really upset by his drug problem but at the same time they might think that you're the child who's good so you deserve all of their attention and "lessons" since you are the most reasonable.