The insurance industry is worth another ~5trillion USD annually. The name of the game here, of course, is predictive analysis and I'd bet that my Netflix recommendations are more accurate than any assessment any insurance company has ever made of me.
I think you'd have diversification up the wazoo in extremely short order.
Edit: accuracy
This seems unlikely. Is this a top-line number? Why aren't existing VISA/MC processors the largest companies in the economy? The number you just gave is orders of magnitude higher than Apple's profits.
A couple minutes Google searching suggests that being a card issuer puts you in a relatively low-margin business with absolutely enormous network effects.
Edit because HN isn't allowing a reply: these numbers are industry revenue, not profit.
https://www.bcgperspectives.com/content/articles/financial_institutions_pricing_global_payments_2014_capturing_next_level_value/
http://data.worldbank.org/indicator/NY.GDP.MKTP.CD?order=wbapi_data_value_2013+wbapi_data_value+wbapi_data_value-last&sort=descIt's revenue, not profit, because I'm coming at this from the perspective of money (potentially) wasted. It's all in the first link.