Altcoins can rise faster than Bitcoin, that's true. But they can also fall much faster, or even go to zero. For Bitcoin, we can say that this risk has now passed. The chances of waking up one morning and seeing Bitcoin at zero are now slim to none. But all altcoins, even the biggest ones, have this risk.
Here you need to look at the risk/reward ratio. Those who have low capital and want to increase their money quickly invest in altcoins by taking more risk. Nothing can be said about those who buy coins with this realization. But for individuals and companies with high capital and low risk appetite, Bitcoin is still the best choice.
Just like the basic law of gravity, what goes up, must eventually come down. When you throw a ball in the air, it comes down faster than the speed it went up, the same thing applies to altcoins. If it takes a week for an altcoin to reach $50 from $10, it is going to take one day or maybe a couple to get back to $5 from $50. So you are right, altcoins are risky because of their extremely volatile natures, those who can bear this risk tend to buy and sell altcoins, and those who think it doesn't suit them, go for Bitcoin.
For industrial investors, they can't afford to lose large amounts of money, and they know if they invest money in an altcoin, there is always a possibility of their investment losing a lot of value in case the price crashes in no time, giving them no chance of liquidating their positions and getting their funds back with only a small amount being lost because the movements are often sudden.