Time travel machines are expensive.
So, to pay for the cost of building and maintaining a time machine, I’ve bought an abandoned mine.
In the mine, I found a cache of brandy and wine that had been left to age for a hundred years.
After I auctioned them off, I was able to build the time machine.
Then I bought the brandy and wine to send back in time.
“What about going forward in time?” said an assistant.
“Sure,” I said. And I went ahead a hundred years.
The world was a burnt-out radioactive husk.
(And the wine was spoiled.)