well, as you can see bitcoin is rising pretty fast these days and with each step other altcoins specially ethereum are getting dumped harder and harder. and best case scenario is that they go down against bitcoin.

for example ETH is not worth 0.046BTC and a while ago it was worth 0.07BTC and not so long ago it was 0.14BTC.
this means if you sold 10 ETH a while ago you could have gotten 1.4BTC but now you are getting 0.46BTC ($9100 versus $2990) that is what you are getting now.

by the time fork happens you may get 0.04 or if you are unlucky there may be a bigger dump and you get 0.03 per coin.

this is the "danger" you forgot to see.