Market cap vs volume is your answer. We dont need to know everything just follow whales.there is reason for choising this coin.they may know something we dont know.
It's just that easy:
If you have much money you can buy many coins. If the coin looks interesting (much fluctuation, much transfer volume,...) there is a good chance you can buy in to a cheap price and sell it to a higher price with a small profit. Through your amount of coins the small profit multiples. Thus the whales don't know anything special, they just earned a few easy bucks over the day...
Edited:
I'm not sure if it's a good advice to say "just follow whales" because whales are often very volatile. And if they buy/sell a large amount of coins they can influence the market and you lost money if you aren't fast enough.