In terms of risk-adjusted returns, Bitcoin worse than index funds. You can get smoother returns using 3x ETFs like TQQQ and TECL compared to bitcoin and about the same absolute returns. Nasdaq 100 has much better sharpe ratio compared to bitcoin. Same for FAAMG portfolio
When I google "Bitcoin Sharpe ratio," every article that comes up shows its ratio to be quite high.
Here's a chart comparing various assets' Sharpe ratios over time, always for the previous four years. Bitcoin's is at top of the chart, staying over 2 and sometimes over 3: http://charts.woobull.com/bitcoin-risk-adjusted-return/
In terms of absolute returns, TQQQ has done well but not so well as Bitcoin. Since 2016 TQQQ has done 12X, compared to Bitcoin's 85X. Since April 2013 (as far back as Coingecko goes) TQQQ has gone up 37X, compared to a Bitcoin's 272X.
As a bonus, Bitcoin has a long-term correlation with the S&P500 of only 0.01, according to the Forbes article linked above.
If you're holding as long as most people do index funds (i.e. 5-10+ years), historically you would have been way better off putting that money into bitcoin. Even taking this crash into account, I'm way up on crypto compared to my 401k. Not going to stop putting money into my 401k though, for the sake of diversification.
