Again, this notion gets into the heads of many and rarely works. Ulic Qel-Droma famously fails. Cade Skywalker only got out of it because he has a very unique relationship with the Force and absolutely shuns power and attention. Relin Druur is the only light-sider I can think of who rationally used the dark side for good, and that happened in a book which presented several non-traditional Force philosophies, so the book was already alt. And Relin Druur died before he could be corrupted by the dark side.