But back in a time when life was not as good, for even rich people, as it is today. Not to mention medical care or even pain medication or air conditioning or any creature comforts (I'm remembering when cars didn't have even electric windows when I was really young).
Would you rather have 10 times the money you have and be back in the 1930's?
Similar also to computers. As anyone who has worked with a teletype, floppy drives, punch tape, or green ascii terminal can attest to vs. being able to ssh into your server from an ipad mini.
If I could keep my current knowledge, yes I think so. "Hey, guys, here's some capital; look into these 'semiconductor' things..."
I recognize that this is deliberately missing your point, however.
The amount of technological knowledge our civilization carries is enormous, and even if you are extremely knowledgeable, you are unlikely to know even 1% of it.
So yes, you would be able to move civilization forward in the magnitude of a few months. But that's about it.
However, I do think you are severely underestimating the benefits, for technological progress, of:
1) Knowing that things are possible, 2) knowing approximately where to look, and 3) having a large (and growing) pile of resources to put behind these things.
The only way you get to the notion that he was the richest ever, would be to speculate on what his empire would be worth today rather than just the dollar figure inflation adjusted.
Most likely, Bill Gates had the greatest private fortune in history at the peak of the Nasdaq bubble. Inflation adjusted it would be worth upwards of $150 +/- billion today.
http://www.nytimes.com/ref/business/20070715_GILDED_GRAPHIC....
EDIT: Wikipedia meme, move along.
There is though still $120+ billion on his children in that list.
Sam Walton was listed as being worth $7.3 billion in 1990: http://money.cnn.com/magazines/fortune/fortune_archive/1990/...
If your audience does shop at Walmart, or knows people who do, then pointing out Walmart's jaw dropping numbers will not be a good device for illuminating the importance of market validation. In fact it could encourage them carry on with the potentially mistaken assumption that the entire planet's needs/problems are the same as their own.
the waltons are definitely number two, if not number one.