BCDBTC
Bitcoin Diamond / Bitcoin
crypto

As an example.
You own Bitcoin, and when you die you want that Bitcoin to be automatically transferred to your sister. 
Bitcoin cannot do that. You need to store the keys with a lawyer who then passes them on in the event of your death. BTC requires the system to function because yes it is hard money, but it is "only" hard money. It doesn't do anything else. 
A smart contract means you can program your money, and set up a time locked  transfer, or automatically pay out loans, or prove ownership of things, track things, and perform actions when certain criteria are met like paying it the winner in a poker game without having a centralised casino as the third party(this still cannot be done by any chain). I hold NFTs that are tied to African housing and mortgages which pay me every month. You can't do that on Bitcoin because there is no way to do it.
Bitcoin was the first hard money, but litecoin is equally as hard, as are the dozen or so variations like BCH BSV, BCG, BCD...and so on.
Cardano is fixed cap and provably as secure as Bitcoin. Just through a different mechanism. A window and a door are the same but different. 

As an example.
You own Bitcoin, and when you die you want that Bitcoin to be automatically transferred to your sister. 
Bitcoin cannot do that. You need to store the keys with a lawyer who then passes them on in the event of your death. BTC requires the system to function because yes it is hard money, but it is "only" hard money. It doesn't do anything else. 
A smart contract means you can program your money, and set up a time locked  transfer, or automatically pay out loans, or prove ownership of things, track things, and perform actions when certain criteria are met like paying it the winner in a poker game without having a centralised casino as the third party(this still cannot be done by any chain). I hold NFTs that are tied to African housing and mortgages which pay me every month. You can't do that on Bitcoin because there is no way to do it.
Bitcoin was the first hard money, but litecoin is equally as hard, as are the dozen or so variations like BCH BSV, BCG, BCD...and so on.
Cardano is fixed cap and provably as secure as Bitcoin. Just through a different mechanism. A window and a door are the same but different.