Rivian's shares have fallen dramatically from their 52-week highs, but don't rush in just yet. The company still has a lot to prove.When Rivian Automotive (RIVN -0.10%) came public, investors were initially excited by its prospects. And then reality set in that building a profitable electric vehicle (EV) company from the ground up might be harder than it seemed. The shares have fallen dramatically from their highs at this point.But before you rush in thinking that you've found a bargain, it is important to ...