Remember there is only one king of crypto market and that its bitcoin. Rest all alt coins are like followers of bitcoin. When bitcoin goes up alt coins goes up and vice verse. Alt coins are not in a position to move the market on there own.
Yeah, as per many veteran members of this forum, we do not need any altcoin investments as bitcoin itself got all the power of good returns for our money. I agree with them because as per them we do not need any diversification in this crypto space.
1. Btc pump then alts dump
2. Alts pump then btc dump
3. Both btc and alts follow each other
They all happen during their time, and by the way the third scenario you have mentioned is not really how it works. Yes a lot of altcoins might follow Bitcoin to whatever directions it goes to because they correlate with BTC at about 90% (more or less), but it is not every altcoins in the market that correlates with Bitcoin and when you match some of them you will see that they have like 5% or even 0% correlation with bitcoin. So there is nothing like all alts following bitcoin, the right way to put it should be BTC and some alts follows each other.