I think about it almost like a collectible. It has value because lots of people think it has value. This is in contrast to a commodity like steel which you can actually do something tangible with.
Someone above mentioned gold and that's probably a decent comparison. There's a limited supply of gold and folks have assigned a value to it despite it having pretty limited use cases to actually make something useful with it.
So what are the uses for Bitcoin? The legitimate uses are to store value outside of traditional currencies like a piece of art and to exchange currencies. Buy a Bitcoin with dollars and someone will pay you for that Bitcoin with pesos. You could do the same thing through the traditional banking system or someplace like Western Union but Bitcoin might eventually be a little cheaper or easier.
The illegitimate uses are to move money outside of a country with currency controls like China and to buy illicit substances like drugs. Those transactions can still be traced and tracked but no one really does that.
It's an investment but I don't know how to properly value it and I'm not sure anyone else does either. Is it underpriced today or overpriced or the right value? I'm not sure there's a good way to tell. Your friend that says you can't lose is absolutely wrong.
I think the best reason to invest in it today is to talk about it with other blockchain dorks about how much Bitcoin you own, what shit coins you're taking a flyer on, and what society will look like in x number of years after blockchain takes over. It's honestly not that much different than amateurs investing in individual stocks in the stock market. I wouldn't invest my nest egg in it but if you feel like investing a little bit that you could lose, it gives you something to talk about and something to learn about.