stop loss is not that good in general although it is pretty useful in some cases. when it comes to bitcoin things become that much worse because of the high volatility and when it comes to altcoins using something like stop loss is a lot riskier because of the manipulation (pump and dump) and the high volatility that it causes.
Actually when it comes to a very volatile market, stop loss is not something anyone should joke with and it is an important part of trading to learn.
The only problem I usually have with people though is that they are always in a haste to learn and start making money and all the necessary things to know are not always touched by them. Stop loss can affect your trading most of the time when you do not even know where you should be placing them and how you should be placing them when considering the volatility of the market.
Yes, there is a huge manipulation in the crypto sphere, but at least, to always be in the safe side, considering using a stop loss or not, I would say the best way to be safe is just to use it.