I didn't know there was a source for dividend adjusted charts like that one.
Understand that common Dow, S&P 500 etc charts don't include dividends either. So I'm guessing you're comparing GOF with dividends to the S&P 500 without dividends.
Key thing tho is that GOF is leveraged, S&P 500 isn't.
I'm not saying GOF is a terrible fund. But it uses some gimmicks that make it look very good under specific circumstance. Some investors may be fooled. Over a few years GOF's high fees will take a toll.
My SPY index fund has an expense ratio of about 0.08%.