Well this bubble will pop one day. The thing is we don't know when and just can wait. But as longer as keeps on going the more of it might floog back into Bitcoin. And in the meanwhile Bitcoin grows as well because everybody who wants to get into alts has to buy bitcoin first.
The only thing I'm a bit concernded about is that on the next big conference, Consensus in New York, some actors may try to spread some new FUD and rumors to create turmoil in the market again.Pretty sure lots of shitcoin pumpers will be there as well. Events like this can be used pretty good for that.
Probably some altcoin needs to purchase BTC first to be able to trade but the majority of altcoin in the top coinmarket cap can be purchased in USD or other major currency. If ever it has an effect on bitcoin probably it is very minimal. I guess it depends on what kind of FUD those some actors have in their hand to outweigh the good news about Bitcoin. Remember this adoption stuff had outweighed the negative effect of this scaling debate.
Do not be afraid of lower prices. For crypto currency - this is a natural phenomenon. Everybody expected this correction for a long time. But this is a very good time to buy coins