Maybe Bitcoin doesn´t need high merchant acceptance or much actual trade to
be a success. It depends on what the main use case of Bitcoin is in your opinion.

I´d argue that Bitcoins main use case is to be a censorship-resistant store of value.
Without possible 2nd layer scaling solutions like the Lightning Network Bitcoin is
inferior to credit cards in terms of transaction times. However, Bitcoin has a known,
completely predictable supply and issuance rate unlike all fiat currencies of the world.
If Bitcoin is indeed a store of value it could be a great success irrespective of whether
it is actually used for payments. I concede that this may not have been the initial
vision of Satoshi Nakamoto, but maybe this is the true purpose of BTC.