I've been thinking lately why I've been
buying a lot of altcoins this week and not last month, or a few months ago, or a few years ago even. Then I realised the natural cycle of events that appear to be occurring in the market. I've been waiting to invest in more altcoins, but am doing so with Ethereum.
Late last year, everyone wanted to buy up Bitcoin, as it went from $10K to $20K as well as beyond. After passing $20K, we saw Bitcoin's market dominance drop from over 70% to now around 60%, despite the price being back at $40K. While Ethereum dominance has increased dramatically.
Shortly after, next month in January (last month), Ethereum reaches it's all time high as the largest altcoin in the market. Today, we are seeing what appears to be the first signs of Ethereum losing dominance against speculative altcoins (although as well as Bitcoin today admittedly).
There are those who bought up altcoins with fiat last year, as they bought themselves Bitcoin, even if initially they were to lose a lot of BTC/ETH value, they would remain good investments for the future (if done on solid projects). Some of these are still down, but at new ATH against fiat at least.
Last month was when Bitcoiners were selling their coins for altcoins that were at enormous discounts against BTC (80-90%), the same tokens that had held their value against the dollar or even gone up 2-4x. Because one persons take profit level is another's buy entry it seems.
This month, after Ethereum's impressive rally from $500 to new ATH at $1,763, there are tokens that are looking very cheap against Ether or breaking out to new ATH, despite already doing so against BTC last month and some time ago against the dollar. Anywhere between 2-4x it seems.
The idea that altcoins can be cheap and discounts against Bitcoin and Ethereum (50-75% still), whilst at premiums against the dollar (100-200%), is exactly why these altseasons occur. There are still more investors who want to buy in as they see the potential from the different investment angle. The final ingredient for an explosive altseason is the increased speculation from traders from other sectors joining in.
The best way to illustrate part 3, would be the following chart. Note how speculative altcoins lost 58% of their dominance to Ethereum since July last year.
While it may seem like altcoins are over-extending against Bitcoin (possible they are), to see they are still down 48% against Ether:

Don't be scared to buy the high against fiat, if you're buying the low with ethereum

TL:DR1. The coins hold their value from stable dollar buying/selling or get pumped by fiat currencies by new money (while they generally lose Bitcoin value)
2. Bitcoiners diversify into speculative altcoins for the satoshi gains (while they generally hold or continue to lose Ethereum value)
3. Ethereum hodlers diversify into speculative altcoins for ether gains (finally outperforming both BTC & ETH, regaining their dominance)
4. Traders push the price higher, newbie traders from other sectors join in
5. The bubble inflates as retail throw more fiat currencies in