Sebastian will always remember the moment he lost £407,000, with equal parts anger and shame.
The night leading up to it had been otherwise forgettable.
He and his wife watched a series on Netflix, before she went to bed and left him on the sofa messing about on his phone.
Then he received a Twitter notification with news from Elon Musk.
Sebastian told the BBC: “Musk tweeted, ‘Dojo 4 Doge?’ and I wondered what it meant.
“There was a link to a new event below, so I clicked on it and saw that he was giving away Bitcoin!”
Sebastian followed the link to a professional-looking website where the Bitcoin giveaway looked to be in full swing.
There was a timer counting down, and the website promised participants that they could double their money.
The competition was apparently being run by Elon Musk’s Tesla team. It invited people to send anything from 0.1 Bitcoin (worth approximately £4,300) to 20 Bitcoin (approximately £860,000), and the team would send back double the amount.
‘Take the maximum’
Sebastian double-checked the verification logo next to Elon Musk’s name, and then tried to decide whether to send five or 10 Bitcoin.
“‘Take the maximum’, I thought, this is definitely real, so I sent 10 Bitcoin.”
For the next 20 minutes as the timer wound down, Sebastian waited for the prize to land in his Bitcoin wallet.
From his house in Cologne in Germany he sat there refreshing his screen every 30 seconds.
He saw Mr Musk send a fresh cryptic tweet and felt reassured that the giveaway was real.
But slowly the timer on the website ran down to zero, and Sebastian said: “I realised then that it was a big fake.
“I threw my head on to the sofa cushions and my heart was beating so hard. I thought I’d just thrown away the gamechanger for my family, my early retirement fund and all the upcoming holidays with my kids.
“I went upstairs and sat on the edge of the bed to tell my wife. I woke her up and told her that I’d made a big mistake, a really big mistake.”
Sebastian, who asked that the BBC didn’t use his real name, didn’t sleep that night.
Instead, he spent hours emailing the scammer website and tweeting the fake Elon Musk’ Twitter account to try to get some or all of his money back.
However, he eventually began to accept the money was gone forever.