In fact, he collapsed from his brain tumor at the bank that he robbed in his fantasies. We see Alec die and then hear his voiceover narration wishing his friends well and saying he hopes they live rich lives and can see each other again someday.
In reality, he passed out from his brain tumor while fantasizing about robbing a bank. We see Alec die and later hear his voiceover expressing well wishes for his friends, hoping they can lead rich lives and meet again someday.