I agree with you, therefore if we want to invest to avoid big risks, then we can just invest in Bitcoin, but if you really want to invest in cryptocurrency without being afraid of big risks, then you can invest in altcoin, because investing in altcoin can give us a bigger profits than investing in Bitcoin, but of course the risk of investing in altcoin is bigger than investing in Bitcoin, but my suggestion it's better for you to invest in the top 10 altcoin on coinmarketcap (safer than other altcoin).
Many times we tell people to just stay and invest in Bitcoin because if you're for various altcoins, you are balancing a lot your portfolio which in your opinion is right. But in the actuality is you are diversifying too much that's coming to the point that you are wrongly doing it.
Because instead of having a balanced portfolio by having Bitcoin and you are reducing the risk, you are attracting more risk to the portfolio that you have by having several altcoins which is very true to be risky.