You don't have to use all your money to invest, even if you are not married yet or have other responsibilities, the best approach when planning to invest in Bitcoin is to buy with some percentage of the money you earning, maybe through business or a job.
The economic system prioritizes good management, including investing. Investment is a good step in organizing future finances.
I think you need to explain to him that this is not the style of investing. Even a small amount invested gradually is better than forcing yourself to ask others for loans.
It is not okay to take all the money to invest in Bitcoin as long as there are other savings to cover the daily needs of the family for those who already have children and wife. But as long as that is not fulfilled, then it is better for your friend not to force himself to do it because the market is very volatile.