If you're asking me, personally, I'd improve infrastructure and social programs so that things would generally be better and the economy would thrive on having more money actually in circulation instead of tied up in the constructed bullshit that is stock markets or being stockpiled by ultra-rich people who never use it.

If you're asking my RP character, he'd immediately pump industrial quantities of norovirus and immunosuppressant drugs into the water supply and broadcast the results as several channels of reality TV.