* it's advisable to diversify your investment. The cryptocurrency market is very volatile when for example coin A is having a pump coin B can be having a dump let's say you invest all you had on only coin B you will be headed for loss and regret. Spreading your investment amongst project is quite advisable not only in the cryptocurrency world but in so many other sectors. The future can be uncertain and unpredictable but when you have investment on more than one project you tend to increase your safety
There's really no such thing as diversification in crypto. The market tends to mirror Bitcoin's movement closely, so if you really want to be safe with your "investment", you're free to put all your eggs in Bitcoin (because everything else will fail before it does), but not in any other coin, except maybe the most established alts.
A better way to word this is to be careful with putting money into new "projects" because it's so much riskier than putting money into reputable cryptos.