The process didn't legalize the crimes nor allow the guerrilla to keep their drug dealing money. That's just FUD. The kind of FUD that made uninformed people vote no.
Uribe fought the guerrilla fiercely, but he did it by getting alliances with paramilitary groups that were even worse than the guerrilla.
The peace treaty is not perfect, and yes, there were some concessions made to the guerrilla. Like the possibility to have 10 out of 270 positions in the congress even if they didn’t get the votes, but only for two periods. It’s not easy to negotiate after 50 years of crude war, but all the lives saved with it are completely worth it.