Over the last few years I've asked prety much every person I have met who works hands on in the markets what they think of technical analysis. My anecdata shows a 50:50 split of opinions.
People who have made money using it say its very useful. People who have made money without it say its not very useful. The reality is that a lot of people who luck out like to validate themselves by claiming some form of skill being involved.
Chart analysis is tool that is one method of making predictions and it is no doubt useful in some situations but will never replace the main method of predicting markets...inside information through maintaining a large network of contacts.
TA is less useful for Bttcoin where you can be utterly fucked up by somebody selling some BTC just to buy a new yacht. Its almost meaningless for low liquidity markets like 99% of altcoins.