As to why Paul Grundy claimed that Lloyd could have made more in other businesses, I don’t think it requires that he either knew Lloyd well or was making a guess. Another possibility is that Lloyd boasted to him in those exact terms and Paul simply believed what he said.
Could it be part of a sales technique? For instance, Lloyd could have made more money doing ______, but he made the sacrifice of being a full-time critic of Watchtower instead. So we must support Lloyd's "work" because he is giving up so much more by being a anti-Watchtower vlogger.