Stomach ulcer if left alone??!

Stomach ulcer if left alone??

My 20 year old brother has been ill lately and has been diagnosed with a stomach ulcer, he has asthma and bikes to work, he had breathing difficulties so doctors prescribed steroids. He took a couple and because he coughed up blood , stopped taking them.He now thinks this caused the ulcer- i think its his unhealthy lifestyle.
He now won't take what was prescribed by the docs for his stomach ulcer, what will happen if he leaves it and carries on living the way he does, drinking upto 15 cups of coffee a day, eating crisps, chocolate,biscuits, fried food, fizzy pop and playing computer games until 4am, also high stress levels from his family?
Can it kill him?, im so worried as he looks so frail.

Putting it bluntly yes :( There's a chance the ulcer could perforate and cause him to bleed to death internally. Not very pleasant. I have a stomach ulcer and if I don't take mt omeprazole for a couple of days I start to get pain and bad acids. Acid can burn a hole in his oesophagus. It's highly likely that it's his lifestyle that's caused it but it could of been or HPYLORI (It's a bacteria). You need to tell him how serious this can be...Good luck x