Those are traders who want to buy some cheap tokens or coins and sell it to a higher price in other exchanges. And some new investors are also buying if the project have a great potential to become big in the future. Some investors buy back their tokens at the cheapest price and hold them and wait for project to be fully developed.
traders with large capital are involved in this after evaluating the trend technically on the coins they are targeting.
good volume conditions make them sure to buy at a low price. This is also done by their followers who only believe in the signal given.
of course the traded coins they believe are still on a good track in the market.