With exception of coins you are hodling in the medium to long-term, stop losses can prevent you from losing a lot of money if you're actively making trades and trading in multiple coins simultaneously to the point you can't watch them all. A stop loss forces you to evaluate what your exit point is when a coin drops in value. Sometimes a stop loss can backfire if you don't setup your loss margin correctly, as a rule of thumb I have my margin set at 10%. Meaning if I take a loss, it'll only be 10% of my investment opposed to potentially losing 20,30,40% if a coin tanks.
On the other hand, you should use stop losses in combination with take-profit orders. A take-profit order is the opposite of a stop loss, it's a target exit point where you're happy to take a profit and sell your coins.Just as important as a stop loss, a take-profit order can cause you to sell coins too early for say a 20% profit and the coin goes up 60% or even 100%+. learning to take profits and not being greedy will be a profitable trading mantra to live by in the long-run.Depending on where I see a coin going and what the charts are showing, I might only take a 15% profit on a coin. You should always use stop losses and take-profit orders with one another, unless you're hodling a coin medium to long-term.