The market is now for bitcoin, same as this there'll be market for altcoins. We don't know which is the ath value of bitcoin for this times bullish trend. We're supposed to make our prediction and go choose the trading. Most of the time once after reaching ath it undergoes correction. During those correction there'll be slight fluctuation and then grows again. That's the right time to trade bitcoin for altcoins.
Actually altcoins are doing pretty good, not all but some of the alts like XRP has gained some serious bull run and there is TRX which is slowly starting to lift so now as the BTC market stablized the other markets are on a swing now. I hope bitcoin just doesn't fall now like 2017 because a drop here can really make things worst not just for the BTC market but altcoin market as well.
In the first place, we have no right to stop others to trade altcoins when Bitcoin is in the period of bull run dude.
Correct we cannot stop anyone from doing anything they want, but would you not stop someone who is trying to suicide? Well, I will at least stop that and similarly OP has a valid point because BTC market is going up so the best option is to invest in BTC and avoid trading altcoins for the time being.