I always suggest "Only invest an amount you can afford to lose" for those who want to join in crypto investment because the risk of losing the money value will always be there and I do not think people are ready with that. People must know about this before deciding to use their money to invest in crypto. Without knowing about the price fluctuation, they can panic when they see the price jump down drastically. But unfortunately, people join in the investment because of the trend and not because they search for more info that the investment can help them make a profit.
It is not something unique to crypto though,,, the adage is something applied to every single investment and in fact if you read every contract that you sign with an investment (traditional like bonds or stocks) there is even the same line of advice there.
People think this risk is only in crypto but it is in EVERY investment,,, never forget this and recall it whenever you see someone claim to guarantee profits.