Re: If you could go back in time to ONE date and still have the knowledge you have no
I'd go back to about 1965 and buy up a bunch of collectibles and store them someplace where I could go collect them today. Collectibles such as used guitars that were worth $150 in 1965, and half a million today; collectible classic cars.
Or maybe go to the late 1970s and buy into some selected tech stocks such as Intel and Microsoft.