What’s giving eth value?

I have heard a lot of people say that crypto like ether has value because of things like smart contracts and proof of stake. But why does that mean you should invest in it? Why can’t a company that wants to use these features just fork ether and do everything in house?

Hope this question makes sense…

Edit: My point is what’s stoping a bank from using blockchain tech in-house that lets you make payments faster and more efficient. Would they need to go through ether or another crypto or couldn’t they just develop their own. I know it wouldn’t be decentralized but let’s be honest the average person doesn’t care about decentralization they want to be able to make payments fast and secure and banks want to be able to process them efficiently.