Odd question :) I'd say both then ..,.. Was both for me ;)
That would depend on the peer.
Call it by another name -- say, esprit de corps -- and it can build camaraderie and inspire people to lift themselves. It's the sort of thing that builds successful sporting teams and military groups in which the individuals watch each others backs.
Or call it omertà and it can build a deadly bond between criminals.
Among young people peer pressure can either inspire or destroy.
So I guess the answer to your question is, "It could be either."
It depends on the peer you surround yourself with. If you surround yourself with questionable people, the peer pressure is most likely not going to be a good thing. However if you surround yourself with principled people, they are more likely to convince you to do the same.
Both a blessing and a curse. At least we don't have lateral lines