Money doesn't buy happiness — just ask Marc Lore.
In 2010, the entrepreneur behind online nappy retailer Diapers.com sold the business he co-founded with childhood friend Vinit Bharara to rival Amazon for US$550 million ($755 million).
But despite the eye-watering payday, he immediately fell into depression.
"You think we would have been celebrating, like, 'Wow, we just made enough money that we never have to work again,' that sort of thing. 'Family is set, grandkids are set,' and everything," Lore, now the chief executive of Walmart eCommerce, told Business Insider's "Sucess! How I Did It" podcast.
"And it was this really depressing sort of moment where we didn't even want to go out for a drink. It wasn't a celebration — it was sort of like mourning. That's what it felt like. And it was really weird. We were like, 'Why do we feel so bad right now?' Like, we just sold this company and made a lot of money, and we just didn't feel great."
Lore, who later went on to sell his next online retail business Jet.com to Walmart for US$3 billion put the reaction down to the loss of purpose.
"I think a lot of entrepreneurship is about ... having fun building something, being empowered to make decisions and run, build your own unique culture, hire the people you want to hire, watch them grow and develop, and go on to bigger and better things, and learn while they're there," he said.
"It's, like, there's a lot of benefit of doing it that go beyond dollars and cents. And I think that hit us, like, 'Hey, in this new structure, this new world, a lot of the things that made us happy are not going to exist anymore.' And so you start to realise there's not any amount of money that can buy your substantial drop in happiness, right?
"There's really no price for that. I think that's we kind of realised. It's like, 'Hey, nothing's really going to change.' We had a nice house, nice cars, clothes, food, like, we were living fine before. It wasn't like the money was going to suddenly bring us from poverty to sort of sustainability, right?
"And we knew we'd always be able to make money — we had good, you know, salary earning potential outside of this. So I guess the money really just didn't do it."
Other entrepreneurs have had similar reactions after selling out. In 2015, Minecraft creator Markus "Notch" Persson revealed how he had "never felt more isolated" after selling his company Mojang to Microsoft for US$2.5 billion.
"The problem with getting everything is you run out of reasons to keep trying, and human interaction becomes impossible due to imbalance," the Swedish developer wrote on Twitter, adding that his girlfriend had left him because she was "afraid" of his lifestyle.
Persson, who created world's second best selling video game of all time, added that he didn't want to be like Tesla founder Elon Musk and "try to save the world" because it would "just [expose] me to the same type of a**holes that made me sell Minecraft again".