yuo should always participate if you don't have a GC. You can win and get an immigrant visa even if you already have a GC.
let's see... If somebody's USC husband refused to file I-130 for his stepchild outside the US, one can relinguish her marriage-based GC and go for the DV GC, and her child will get a derivative DV visa.
Also, if that someone does not wish to have a conditional GC, she may also win a DV lottery and her GC will be unconditional, provided she gets the DV visa.