It depends on one's ability.There are many people who have invested money but even if all the money is gone, it cannot affect their life. Again, there are those who lose a little money but it affects their life a lot.We are advised to invest only what we can afford to lose.
I agree, despite the fact that they invested almost all of their savings they can still survive and live normally where they won't reach shortage of money. Let's say that two different person have the same income, but they spend money differently where the one is practical and budget his money while the other one spend too much money on nonsense things which is not necessary. Do you think they can invest also the same? Of course not, the person who spend a lot might say that "he lack money for investment because his income is not enough" which is true since he don't have enough balance to invest. It's not only on the assets but also the techniques. You can afford to lose money if you think you can budget your money in a long period of time.
Because it would be foolish to invest all the money in order to earn extra profit. Most people invest all their money in cryptocurrencies when they see that they are getting more from a small investment.Later it can be seen that due to excessive greed, he loses all his money and becomes poor. As cryptocurrency makes people very rich as well as poor, we face loss due to not following the basic rules.
Investing all your is not a good move, imagine everyday you have to survive without having extra budget for your expenses and needs. It depends on people how they handle to invest while budgeting their money so in the next few years they will gain huge profits. Even gaining a small profit is a big thing for people to earn in starting a small investment. We all start from small before having a huge investment. A wise decision in money could also make you rich but it's true that being greedy could loss your assets.