No wait for BTC $20K+ rally -> ETH will dump and you will buy much cheaper!
Wait a little more, eth may dump but don't be scared because it will bounce back and make good money for you. Though people say negative things about eth I am still confident that this coin can make our future bright.
The interconnection of the courses of all crypto-currencies - if a grandiose jump is planned for one of the popular coins, for example, in bitcoins, then the mass excitement of the means for earning on the growth of its rate begins on the exchanges. At the same time, the supply of the remaining currencies is growing, which reduces their rate.