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.
That's about being optimistic when someone invests and I'm also like that whenever I've got other investments on the process. I just think that everything is going to be well but before thinking like that, I make sure that I know what I do and so I don't regret with my decisions and it never happened to me for having bitcoin. What I just did wrong is when I need to sell forcely because of the circumstances that I've faced before and just as I've said, it changes with things that we deal personally. So if OP is in good condition and don't have to think a lot of circumstances, he has to take that opportunity once and for all before anything happens. Because if it does, he may not be able to invest just as what he's said about placing 60% from his savings but as he do that, he needs to carefully review his status first if it's really doable.