It will be very difficult to dump the market further(it is possible, but it will be very difficult and dangerous), because the miners are already working at a loss on some coins, like ethereum. Bitcoin almost fell to mining cost price, so, i think, it worth to start to buy now.
Recently i read something interesting regarding investing and it sounds like this: buy from the pessimist and sell to the optimist if you want to make profit. This is the time to buy.