There was never a way to gamble safe and there also never will be a way to gamble safe because gambling is not safe and its something that you cannot do safe too.
You can do some things to have minimal losings but that is all honestly.
One way of gambling safe is not to use your own money to gamble. So one way to get other people money is faucets. However, not related to gambling, there is also ways to get other people money like crowdfund to design a product and so.
and who will allow you to invest his money in gambling, you cannot some one else money in gambling, i think the only way to play gambling safely is to limit your gambling amount, you should play gaming with such amount that you can bare to lose.