What percentage of someone's income do you think is advised to be used for trading?
Shouldn't you calculate the percentage of money you may not need for the next six months (after deducting expenses and emergency funds)? Setting a fixed percentage of income will lead to disastrous results.
The percentage is determined according to the market. In a bull market, I recommend no more than 3%, while the percentage may rise to 20% in a bear market and for long-term investment in Bitcoin.