Is Helping A Heroin Addict Worth It?

Okay, so I need some advice...

I have this friend that is in jail...he has been there since Christmas..Yes its kinda drug related (violation of probation). Anyways..yada yada...they just added more charges 2wks before he is supposed to get out of jail, I know the new charges are something he prolly did when he was using. he is also only 21yrs old and has no family here to help him. I feel like I really want to help and I don't know why. We hung out before so I got to see him sober and normal... I know he went off the deep end for a couple of months and ended up in jail... Do you think I should help him or would it be a waste of time and money? Do you think he will just take off and get high when I bail him? 3months in jail seems like long enough to detox (the hard way). So what are your thoughts, is helping a heroin addict worth it in the end?
you could help them,but i think its best for them to prove to you they are ready to stop using ,being clean in prison is no guarantee ,that they will stay clean ,if they have a 12 step program in mind attend meeting they may be ready to stop using my experience is that it took a lot more than prison to stop me using and i would say anything to get what i wanted and believe what i was saying the person i lied to most was myself .Be carefull