So, in theory, I could transfer $126,000,000 for $2 and get it in one day.
with bitcoin, you can transfert 1 000 000 of BTC in 1 hours to the bottom of the bresil ... for 0,002 BTC

it's not the theory.
it's that, bitcoin.
the network job.
If I had a hundred million dollars I don't think I would worry about them charging me the cost of a two liter bottle of soda for the transfer because they can be held accountable for the transfer and it's insured. The last one business day (8 hour) guaranteed transfer I did cleared the bank in about 1.5 hours. Same-same.