Satoshi is from the future. In his timeline, he was very poor and bitcoin was invented in 2012 by someone else.
He sold everything he had and bought a one way ticket to come back in time to start bitcoin himself, so his future self would be a trillion-air and not need to travel back in time.
This could be reasonable. I guess there could be a completely logical reason to not time-travel to the most major events we've had in Earth's history (assuming they weren't already tampered with) - so even though we might discount time-travel theory just because we haven't noticed it, it's possible Bitcoin was the first event considered important enough to tamper with. Starry-eyed, I know. In a FTL future where Satoshi may've come from, events are likely much more significant to many more people (assuming the number of people on Earth over the past tens of thousands of years doesn't create any exponential function with regards to the number of humans colonizing in space in the future, which seems plausible). Fiat has absolutely no place in the FTL era. You go visit a moon on YX-0038 with a briefcase of USD or rubles and they might pay its fuel value... so maybe a micro-satoshi, or just a beer to cheer you up. Crypto can be sent far into space already -- there's really nothing preventing extremely long travel, though you'd probably want a particular individual planet to handle most of the actual transaction processing due to latency -- actually, I guess it'd make sense to have unique cryptos for each "sector," ironically bringing back one of the same issues Bitcoin was supposed to solve: geographical boundaries restricting value flow. I'd be surprised if there weren't already a paper or few on intergalactic Bitcoin, though.
More likely, though - Bitcoin was never invented in the "previous past" - at least, it wasn't open-source. If it was already invented and open-source, it would've been silly for Satoshi to not copy-paste the future past's code and to instead give us a kludgey, insecure client. Since he didn't copy-paste, he probably slapped together the code after a couple crash courses and tried to reverse-engineer what happened in the future, and in that case, Satoshi would not have needed all the input he took during the time he was developing. OTOH, it's also very possible the code of the future relied on so many not-currently-invented dependencies, it had to be re-coded from scratch. Satoshi may've been a coder from the future but didn't count on having to write Bitcoin in such a now-obscure, archaic language, though the original daemon being Windows-only would imply Microsoft will probably always dominate the OS market (or it was otherwise the only OS Satoshi could find a copy of in the future).