Bitcoin is not too slow, Bitcoin fulfills the role of currency issuer and final settlement. (Reddit Bitcoin)
"Ultimately, bitcoin is not competing with Visa for supremacy in global payments. Instead, bitcoin is competing with the dollar, euro, yen and gold as money, and any comparison to Visa, its transaction volume or transaction speed is fundamentally flawed. Bitcoin fulfills the role of currency issuer and final settlement. As a result, the proper comparison would be between bitcoin and the Fed as currency issuer and as a clearing mechanism. No one makes the mistake of confusing the functions of Visa for that of the New York Fed, but for some reason, the comparison is often made between Visa and bitcoin. "
I had an epiphany reading this article and especially this paragraph.
Bitcoin is the basis to which a payment system such as Visa/Mastercard will be built.
Lightning network being a good start but many more of these innovations to come and help scale Bitcoin based payment systems.