When we are making decisions on this kind of instance, we need to focus on both the present and the future consequences of taking such decision in working together with people, not everyone likes a joint or partnership investment because the later end will always looks shady amidst the fellow investors and everyone finally partways, anything that has to do with money must be on a sole proprietor business ownership and not joint task, but there are situation whereby some business could actually requires such, we can take the risk in starting even though the relationship with them in doing business together may not last, joint effort is discouraged in some situations and some settings awesomely welcomes such an idea.
This is why I would never do this because there aren't that many people that I would be believing to do something like this. I would feel that I am about to get screwed over and that's why I rather not do it at all. I have once did it in my life as a "wager", like I gave my money to a friend who said he could double it and said that if he can't then we all knew that he had enough money to pay me anyway, and he did, and proved it as well like not that he put his money on top of it, and even then I was scared like crazy.
I did it because it was a bet between friends, not really care about the outcome of it to be fair, I just wanted to bet with a friend, and if I felt like that with a friend, it would be impossible for me to do it any other way.