I do not understand. I can send money directly to anybody in the world using Bitcoin with ZERO risk.
It's not zero risk. There's a risk that a 51% attack will devalue the currency. There's a risk that a speculative bubble will collapse and devalue the currency. There's a risk that Bitcoin will collapse and leave you holding something that's worthless. These aren't high risks, of course, and it may make perfect sense to take them. But it's not zero risk.
Or using ripple? I'll give $10,000USD to my fiend, he give them to his friend (then 6 other I never saw)... and if one of them is cheater I have lost $10,000 USD. This is Ripple ? If somebody buy me a coffee I can give him $1M ?
No, that's a misunderstanding of how Ripple works. You can only lose money if someone you chose to trust betrays that trust. Other people defaulting cannot harm you.
Payment paths only exist for the instant a payment is made. After that, it's just balances between people who have chosen to trust each other.
To use a check analogy, say you pay your landlord with a $400 check. He deposits that check in his bank. Now your bank owes you $400 less and his bank owes him $400 more. So he considers you to have paid him $400. But if his bank collapses, that doesn't harm you. He chose to trust his bank and his bank accepted the check. It's only if your bank collapses that you may be out money.
You gave him a $400 check that was acceptable to a bank he chose to trust. That ends your end of the bargain. Him getting the $400 from the bank that he chose to trust is his problem. And, of course, my bank paying his bank is his bank's problem, not mine or his. If his bank agreed to accept checks from my bank, then if that goes wrong that's their problem.
You can never wind up being owed money by anyone you didn't choose to trust.