Bitcoin is the best performing asset class in the 2010s, while gold has been a store of value for thousands of years.Each asset has distinct advantages and disadvantages, and both are hedges against a decline in the value of the US dollar.Why I think Bitcoin and gold are complements, not substitutes, and serious investors should own both gold and bitcoin.Bitcoin has more catastrophic risk than gold does. I worry about what would happen to Bitcoin in the event of a 1-in-150 year electromagnetic storm.Bitcoin has factors growth and momentum, while gold has value.