NO........ Never.
He is just ur friend, image we are unable to collect back the money from our own relative !!!! yet, they are buying new car, ipad... wtf...
my case, it is just few K yet, been delayed for few years, and they keep on upgrading their gadget and car whereas, no money to pay me back +_+

there is always 1 assumption to remember, once you given the money out NEVER EXPECT to get it back !!! this will make u feel better. Oh, your friend is paying u back, THIS CONSIDER AS BONUS !!!! and you are lucky to retain such friendship