First off, I don't think Bitcoin hitting 100k and above happened within a twinkle of an eye as you said we all witnessed how long the speculation of the price of Bitcoin hitting 100k this year was predicted and it became a reality as predicted this year and the price even went ahead to cross 110k.

Seeing the massive increase in the price of Bitcoin and the growth of Bitcoin investors before and after the price hit 100k, I think it is one of the biggest motivation of Bitcoin holders to keep holding knowing that they have got nothing to lose if they don't sell as a result of panic and to other investors who are believing that other cryptocurrency will become like Bitcoin some day, I don't think the recent increase in the Bitcoin price should motivate them much because I doubt if the other projects where specifically designed to perform the functions like Bitcoin.

Well pretty much I say. If bitcoin going up, expect some coins to go up to making the market bloom again but when bitcoin goes down, altcoin dumps too. Obviously bitcoin is the market leader for crypto and we can totally grasp that when we observed the market.

Just now bitcoin having a retracement and all coins follow through much worser I think.

When we want to consider altcoins, it is because we have heard about how bitcoin all started and we think going for others too may give the same accurate results for us instead of us waiting for the bitcoin market to crash or plummet in other for us to invest, just as the default has been set, that bitcoin is the lead while all other coins follows in cryptocurrency, also, we cant deny the fact that each coins have their season, but in most cases, bitcoin determines for others.

The Bitcoin price increase to the 6-figure level was long expected, and it only took its time to finally reach there, which many can say the Trump election winning fastened up the process to why it got there real quick, which I also agree with that.

Bitcoin reaching that height shows that there is more to still be achieved, and it has made way for other currencies to also have their own fair share, which most have broken to their ATH and create new ones too. We can say that this is one of the influences and effects of the Bitcoin price increase.

If I’m not mistaking op is trying to state the fact crypto growth depend on bitcoin growth so they can also be profitable, no doubt bitcoin market growth impacted few coins. As the name imply altcoins, I’m not surprised because every coin is just like a second option compared to bitcoin, the impact most of this coins get during times like this is the hype and price whenever bitcoin price is high it’s certain few coins will rise else there’s no comparison neither will anyone miss an investment chance.

One of the effects of the rising price of Bitcoin is the increased confidence among investors. Whenever this happens to Bitcoin, it often generates new interest in liquidity for altcoins.

I also think this varies depending on the coin and timing. For major projects like Ethereum, Bitcoin's success can spark new waves of institutional and retail adoption. As for smaller or less established coins and tokens, it can either inspire speculative buying or leave them overshadowed as the focus remains on BTC.

The growth of Bitcoin is driven by the interest rate that is willing to buy Bitcoin at any time because when it can continue to grow every year of course there are other effects such as the increase in the price and value of Bitcoin itself so the same thing can also happen to other coins when the community of other coins can continue to grow. But from what we have seen now is quite real where there are many coins that have experienced a price drop including Bitcoin when there was a rate cut from the FED although I thought it was just a coincidence.

We can say the same when BTC is down, like now.
At least for a little while - we will see some people have shaky thoughts - but those who were for a while on the market won't even look at such things.

The reality is like this.

When Bitcoin price rise 10%, altcoins price rise 3%.

When Bitcoin price rise 30%, altcoins price rise 10%.

When Bitcoin price down 2%, altcoins price down 5%.

When Bitcoin price down 10%, altcoins price down 30%.

Only some altcoins price rise higher than Bitcoin.

I have sold my Bitcoin to buy altcoins, now I'm in floating loss like 30%.