Bitcoin is what it is now thanks to altcoins, a lot, lot of people join to crypto thanks to altcoins like Doge, and that since years ago.

Just imagine a nocoiner trying to send bitcoin to a wrong address, or made a mistake writing the amount to send like a fee instead.

A nocoiner trying to upgrade his bitcoin wallet without backup up his wallet dat file.

Nocoiners need altcoins to learn about crypto and how to send transactions without fear, altcoins are necessary to practice.

Also the point on just telling a nocoiner to invest +8,000 usd to buy only 1 bitcoin, nobody likes to have .01 or .001, 8k usd is a lot of money for most people around the world

Global population distribution by income
15% are totally Poor   
56% survive with Low income   
13% are Middle class
9%  Upper-middle class   
7%  Highest income

Forget about Poor and Low income people, the income for middle class is around 50-60k usd per year, we really think they can spend 8k usd to buy a single bitcoin

Thats leave only 15% of world people able to invest in 1 bitcoin.

But thanks to altcoins around 29% of world can afford to buy 1 ethereum or 1 litecoin

Thanks to alcoins 85% of world can afford to buy 1 Ripple or 1 Doge

Altcoins are necessary for Bitcoin to survive.