I honestly don't get it why people tend to care about BTC way more than about other coins and crypto overall. Emergence of new coins help crypto evolve.
Because most of the people/investors are Bitcoin investors and most of them invested at its peak when it was skyrocketing at the later part of 2017 and early part of 2018 this will surely answer your question. 
And Bitcoin is no doubt the best crypto currency so far with its really awesome security feature and for almost a decade its system is never been high jacked or jeopardized by hackers.
Not really that crypto ICOs are killing bitcoin it's their own system which is rotating him and affects on different altcoins so no need to worry it's all depending on the supply and demand.
Actually new crypto currency initial coin offerings help Bitcoin to be on the top list of most traded crypto currency and its dominance on Coin market capitalization is freaking awesome.Take a look at this picture below.
It shows 53.7% overall dominance on the whole crypto currency market and every ICO that obviously most of them pairs with Bitcoin and most of the coins or tokens listed on exchangers have a Bitcoin trading pair this obligates the investors to buy Bitcoin first to be able to trade or buy the coin or token they want.