I think this is more targeted at people who don't push towards more aspirational work - e.g. staying in a 9-5 job as a web developer and paying the bills rather than developing a business and being ambitious. They may feel as though they are working hard and applying themselves, where they may be under-utilised and just using "hard work" as an excuse for not pushing themselves.

In other words, the classic "work hard / work smart" contrast.