Is it safe to take 1 bisacodyl 5mg tab daily indefinitely? why is dependence on it bad?

Probably not: Stool softeners, like colace (docusate sodium) or surfak, CAN be taken pretty much indefinitely, but bisacodyl is a stimulant, and there is good and long-standing evidence that continuous long-term use of such drugs produce a "lazy bowel," so that the bowel cannot react normally. Eventually people can't have bowel movements without the med, and tolerance develops. So, I wouldn't recommend it. Find the cause