It is very safe to trade with support resistance but when we learn to trade we forget it after learning it or we are not interested in using it. But the use of support and resistance is very important in trading. Many of us run after strategy and forget or ignore the use of support resistance. The market always respects support and resistance or breaks out and moves in an up or downtrend.
I urge new trades to learn to draw support resistance with great care and observe the market to see the results for yourself.
It's as important at having your entry and exit strategy. But the problem is that new traders doesn't want to learn some basic trading strategies, they just want to go there and trade and then complain when they loss money in cryptospace.
Here is a good read about the subject:
https://www.investopedia.com/trading/support-and-resistance-basics/Yes, I agree that they are not 100%, everything in trading is not a guarantee, but at least knowing the basic and then you can learn as you go along.