I believe it's a combination of greedy miners who only seek short term profit (dump as they mine) and/or miners with cheap to free electricity, constant FUDstorm mostly by ignorant people, lack of investors because there were and are so many scams that virtually everyone in crypto got burned at some point, we're oversaturated with practically hundreds of useless altcoins and then there's the fact that every altcoin is still bound to the price of bitcoin which is lower at the moment than most people would like it to be.