I think bitcoin and cash are both good and we cannot just choose one because we cannot use our bitcoins without cash and we cannot grow our cash without bitcoin, they are interrelated and they work together to give us convenience and income at the same time.
we cannot use our bitcoins without cash
This is not completely true. We can spend our bitcoins, but for now, it is very limited.
we cannot grow our cash without bitcoin
There are tons way more to grow our cash even without bitcoin. There are way more investments that accept cash than bitcoin. Cash is not limited by bitcoin.
they are interrelated and they work together
Bitcoin and fiat are two independent entities. They are just related on exchanges that exchange fiat to bitcoin and vice versa.