Isn't on chain scaling impossible? And isn't increasing the block size just kicking the can further down the road?

I'm a bit of a newb but my understanding is that BCH wants the majority of scaling to be on chain. I did some more research and found out that in order for BCH to achieve it's goal of p2p money for the world then the block size would have to be gigabytes in size. Perhaps even larger. How does BCH plan on achieving a goal that seems to be impossible from a technical standpoint?

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Edit: Thanks for the replies everyone but they've only led me to more questions which are

What about mining centralisation? Wouldn't very few people/companies be able to mine blocks that are terabytes in size? And all the power will be concentrated in the hands of a few?

2nd edit haha: Does anyone know how many companies mine BCH? For instance i've seen that most BTC mining is does in china and this is a bit of a problem. Is BCH mining more decentralised? Would larger blocks make the problem worse?