Not uncommon. It won't go on for ever. Here's dot com bubble period Nasdaq http://news.bbc.co.uk/1/hi/business/8558257.stmSo why mention these irrelevant examples if they don't prove anything?
The examples given are all flash in the pan investments that peaked once and never again. Bitcoin has had more peaks than a mountain range - each one higher than the preceding one.
Index of railway shares, 1840s http://www.thebubblebubble.com/wp-content/uploads/2012/06/railroadstocks.jpg
This is the Dow Jones index 1929 https://www.marketwatch.com/story/scary-1929-market-chart-gains-traction-2014-02-11