What gives value Bitcoin?

So today I got in a little debate with my good friend about how derives Bitcoin value. He claims that Bitcoin is not worth because it has no backup. I said same about the dollar, except the dollar doesn't have a better money cycle. So we fight and for a bit about centralization vs decentralization, the positive side and negative side and in the finally I set up a Bitcoin wallet to him. So I just wanted to talk about what does actually give Bitcoin it's value.
The number one reason Bitcoin has value is the technology. The technology of Bitcoin makes it so that one group of people could never completely take over. Bitcoin is also convertible in to altcoins. there is a coin exchange where people can come together and work on a way and buy and sell altcoins. another good things with Bitcoin I do want to bring up some of the problems concerning Bitcoin. I think one of the big problems is if the power shut down of the world Bitcoin becomes useless.