Bitcoin bubble? The warnings from history

From the tulip craze to the South Sea and dotcom bubbles, the past teaches us to beware too strong a dose of irrational exuberanceBitcoin is drawing comparisons with past economic bubbles, owing to its meteoric rise this year. Here are some perhaps poignant history lessons:Bitcoin is the first, and the biggest, "cryptocurrency" – a decentralised tradable digital asset. Whether it's a bad investment is the $97bn question (literally, since that's the current value of all bitcoins in existenc