Contemporary artists are more “collectible” than old masters: there’s more of their art out there, you can party with them, you can even hope to discover geniuses before they get “hot.” One downside is that, because the competition’s so stiff, prices can lose all touch with reality. That’s especially true since the majority of today’s most collected art stars are bound to fade into oblivion. (Art history has always done brutal triage.) Here are five highly touted artists whose works won’t all survive as great art and will therefore turn out to be lousy investments. —B.G.