emergency funds should not be invested. because we know that this emergency situation can happen anytime. we can not predict about this. if an emergency fund is invested in cryptocurrency and you need funds but the market price goes down, will you sell it directly.. 
I agree, must not use our savings fund in investment, we must learn how to balance and divide our money. Mostly we used our savings for important things that we need. It is much better to be prepared for anything that may happen and you have your savings because you dont need to worry for the money that you need for that time.