The help Kaiji gets besides Mario and Chang are from people who don't have much to loose from helping him (well except maybe "the center of the world guy" but he had good reason to be pissed by Ando) . All the people who betrayed him where people who had choice between friendship and money, or where driven by jalousy (in the "17 steps" match) and a lot weren't his friend at all (Ando, Furuhata).
I guess we can see here that in the "fukumoto world" good people exist but when things get hard only very few people will do "the right thing". Don't trust people you don't know and when a lot of money and life and death are at stake be wary even of your best friend, let alone a stranger.