How much is that some that you can lose? Only you can answer on how much you're willing to invest, if it's 60% then that's it. Risk appetite of each of us changes based on the circumstances that we're facing. You may say that you're okay with that percentage for now but it could change tomorrow if some unexpected things happen and vice versa.
Before investing everyone thinks he will get the best return on his investment but can see the real result after investing. Because the market has seen many unexpected movements due to which even experienced investors have lost money by huge margins.
Therefore, it is important to manage money in investing so that even after seeing unexpected results, one's financial situation does not go to a very bad level. So 60%-10% is not a fixed amount, it depends on the financial and emotional status of that investor.