If there is a desire to buy altcoins, then the maximum you can allocate for this is 10% of your portfolio, but personally I would not do this. If there is bitcoin and I am confident in it, then why should I buy other coins?
I doubt that in the end these altcoins will grow significantly higher than bitcoin, but at the same time there is a very high risk that this altcoin may not grow, or something will happen to this project and its price will fall significantly.
Even if I know that bitcoin will grow a little less, but I will be sure that this is a reliable investment and nothing bad will definitely happen to it.
It's important to remember that different investors have different risk tolerance and investment strategies, and what works for one person may not work for another.
However, it's generally a good idea to diversify your portfolio to spread out risk and potentially increase returns. It's also important to conduct thorough research and consider multiple perspectives before making any investment decisions. It's also a good idea to stay informed about the latest developments in the cryptocurrency market and to be aware of the risks involved in investing in any coin, whether it's bitcoin or an altcoin.