No, it is not safe. I recommend you to invest on coins that you think has the potential to boom, like WAVES ( well, that's my personal bet and fave alt coin), WAVES is currently on a low price now but you can still try on investing on it , i believe to the potential of WAVES on booming and With all Honesty, i do not think that you can monitor the top 20-25 coins if you invested to all of it, that's situation but if we put reality on that you will be having a hard time monitor the coins. You need to carefully decide on this kind of things and final reminder, Invest something that you can lose. Good Luck.