Crypto might play a big role in your portfolio’s growth if you bought your crypto assets during the market crashes or did DCA.
The percentage depends on your risk appetite. Some people go full crypto but I don’t recommend that route. I prefer to have a more traditional portfolio that mostly has stocks and bonds. Some cash and physical precious metals are also good to have.
In this day and age, if your portfolio doesn’t have any crypto assets, you are playing the game wrong imo.
Of course lot of people wouldn't want to be left out by so doing wanting to venture into cryptocurrency space, though sometimes most of them do make the wrong decision on choice of investment by focusing on altcoin only which I think isn't a clever option and choices. Of a true having different choices of investment and diversification just as you made mentioned is always the best especially that of physical property or landed properties.