My brother attempted suicide in my home after staying for a week. He usually would camp out on mom's couch every few months when he was between relying on his friends good humor. He is moody and at times his acceptance of anyone's help came on his terms. He doesn't understand my anger at his chronic poor decisions made over 20-some years, especially after I had found him laying unconscious in my garage after a failed hanging attempt. He didn't have to see himself on a cold garage floor during a Minnesota winter nor provide first aid while waiting for an ambulance. He didn't spend two weeks numb, in an intensive care unit wondering if his sibling was going to regain consciousness. His version of events is that he is a victim.
After years of therapy I am free of the emotional hooks dysfunctional family members used to use to snag me with. Most of that therapy was for me to learn how not to be dysfunctional and then some to discover the confidence to make healthy decisions interacting with others. It took learning courage to accept the unknown when my generosity was rejected by my brother who always has an excuse or reason why something cannot be straightforward. I hope you can discover this for yourself. What follows my blunt observation of the situation you described. I hope you can see I mean to be helpful but if the shoe doesn't fit, please ignore me.
The narrative you described is that your brother's life story is him against the world. You provided several ways that he makes being supportive difficult. What is dangerous is that you illustrate that you feel responsible for his well being. Perhaps your generosity is a vain effort to stave off the inevitable but done so with all of the best intentions. This is a complicated issue that is not easily solved. Obviously, but rejecting professional help because the situation is desperate...it has probably been desperate often if he has had to rely on you more than a couple of times. Take care of you, and find the confidence to let your brother experience his failures without you cushioning the fall. Maybe the pain will motivate him to try something new instead of relying on you.