Sam was fighting those poisonous frogs. Everyone of those frogs didn't even get to know how they died. You can say that right now Sam wasn't leaving anyone alive. He was killing those Monster as much as he can
After collecting the loot and those dead bodies he once again begins to advance. Well in those loots sometimes he gets materials, and crystals. You can say that until now he did not get any techniques from those monsters. Also even though he was getting some rare materials that could be used to make good armor or anything like that, he was interested in those materials. He could just buy those from his system shop and because of this he only sold those things.