We as investors that are aware of Bitcoin definitely see the worth on it and it's always the best choice. Despite that there have been a lot of altcoins that outperformed Bitcoin in terms of gains. It's not always the case, whilst if you're going to take a look at those altcoins that have gained more than Bitcoin. You can ask and try to find them where they are right now. And as for Bitcoin, it's still here and remaining as the king of this market no matter what new altcoin comes out.
Alts are good for short term gains, if you buy Bitcoin at current $40k price, how much return do you think you gonna gain? 2x, 3x; while returns will be significantly higher with alts when Bitcoin rallies. You are supposed to rotate alt profits back to btc and not hold on to alts for long time, it's proven most of alts don't last long.
That's true about Bitcoin if you're going to take it for the long term. There are conservative investors that would choose that slow growth but in a sense that they're secured without having to worry in the long run. While the experts on this market, earns from Bitcoin and then still gets to rotate the money made from Bitcoin into alts and then after making another profit from alts rotates it back to Bitcoin. Anyone is free to rotate the profits and choices but not everyone is doing the same thing as you've said.