I’ll bite for this silly question.

If I had a time machine I wouldn’t deal with Bitcoin. It would be a headache especially in 2013 if you started selling large quantities. Banks would get suspicious where you got all these funds, they would think Silk Road.

The real money would be to buy lots and lots of stock options near the highs and bottoms. Basically a small $10k put option could 1000x if bought at the right time and doing the reverse at the other side. Stocks have much more liquidity and it’s possible to make billions easily. With Bitcoin not so easy.