Sometimes these things happen; but before weeding people out I would first make sure there isn't another reason people are dropping off a the point of close (maybe the product onboarding or configuration process is complicated.) have you reached out to these folks and asked them to give you some feedback into the process as to why they dropped off at that point. these may very well not be qualified leads for your product but just tossing them aside could mean you miss out on a tremendous learning opportunity and get critical insight into your product. Do all of these leads you're closing have the same source/come from the same place? Happy to connect and help map out a battleplan.