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Minimum risk is possible for the long term but not risk-free or say 0 risk when it comes to bitcoin.
Everything has a risk especially when talking about bitcoin so we cannot say risk-free bitcoin even 0 risk even if it is done for the long term even though bitcoin is still very worth it to do.
In this context for the long term we actually only minimize risk because at least with the long term our risk will be smaller than for the short term but that does not mean this is 0 risk because after all when we talk about bitcoin and invest in it there will be no such thing as 0 risk. Don't because we are too sure that we forget or eliminate important things as if it were certainty even though risk is quite closely related when we are in the scope of bitcoin.
There is no risk-free investment - all have risks, but the risks are never the same. The risks of investing in bitcoin and altcoin are different - it is true that you can lose money, but the big risk of investing in altcoin is that you have no chance of recovering when the altcoin is no longer in demand by investors and the altcoin dies on its own. Bitcoin will never be in that position - it is quite reliable as a long-term investment, but you have to be able to understand the risks and minimize them.
There are many guides on how to control risk and how to minimize it - we can all learn. The risk is not only about the price changes - but also about how you secure your bitcoin and store it. One example of minimizing the risk of bitcoin investment is - do not store your bitcoin online.