My personal viewpoint on all of this:
The market is more efficient than anyone could have previously predicted - two hedge fund buddies sold a $55M btc position in 30 minutes last week.
The market is rapidly maturing - futures trading may be feared as a source of volatility and potential shorts, but it ultimately represents a logical entry point for institutional money. Asset managers understand the bubble implications but are being pressured to establish a bitcoin/crypto position.
Crypto is one of the better ways to get exposure to blockchain today, but the best blockchain investments are yet to come. If you are investing in cryptocurrencies solely as a blockchain play, stay on the sidelines.
If you are not invested in cryptocurrencies today, but want exposure, I would strongly recommend;
1) dollar cost averaging - the markets are volatile, don't try to time them. Sign up on Coinbase, set up a recurring purchase (weekly or bi-weekly) as a natural hedge against rapid price moves
2) do not invest more than 5% of your liquid net worth in this 'asset' class. Said differently, you have to be prepared to lose your entire investment. I believe that btc could be at 25K in 2-3 months and 50K by the end of 2018 and eth at $1k by Q2 2018, but there is an equal risk of total loss.
3) find three people that know cryptocurrencies in and out and follow them closely; don't pay attention to media coverage or guys like Mark Cuban who opine on everything