most obvious investment in my 4 decades as an investor.
I don't know the context of 2009, but just so I could debate about that 2020 investment being "obvious":
Maybe in hindsight it seems obvious to buy oil in 2020. I did and made a lot of money. I sold too early though. Why? Because I'm a beginner. But even if I were an expert... Buying is the easy part, knowing when to sell is the hard part.
When XEG crashed in 2009, maybe it was obvious to buy it at the cheap price of $12. Maybe one investor was gloating around in 2011 when XEG reached $22, doubling his investment. But did that investor sell at that moment? Did he kept holding in 2012-2013? And in 2015+?
The only one thing I know: stocks go down faster than they go up.
Also, sure, there are many indicators telling us that the oil sector "should" continue to go up. But wait, is that because we're the only "geniuses" out there seeing clear? I'm pretty sure there's much more "geniuses" experts in Wall Street who are also buying... So the current price
should reflect the current information that all experts have and current risk of that investment. And there's also the unknown behavioral / momentum factor in play.
So we can't truly know when will this rise stop and how fast it'll go back down, if ever.