The Blink-182 star was diagnosed with cancer in 2021 - but having been so fortunate in his life up until that stage, Mark felt like he "deserved" to die.
"I hadn't told anybody because I thought people would find out I was sick and they'd laugh or they'd think I deserved it," the 53-year-old bassist explained to The Independent.
"I thought I deserved it. I'd been so blessed. Our band get to do things no bands ever get to do. I have an awesome wife and an incredible kid. Of course, the other shoe is going to drop."
After hearing the diagnosis, Hoppus thought: "OK this is my time. I've been lucky for so long and now I'm supposed to die."
Hoppus accidentally shared news of his diagnosis with his Instagram followers, when he mistakenly posted a photo of himself undergoing chemotherapy treatment.
"It was my third round of chemo and every time I'd go, I'd try and post something on Instagram to my close friends and family to say, 'Let's kick cancer's a**' or whatever," said the music star, who is married to designer Skye Everly.
"They had just given me a giant shot of Benadryl to start the infusion, and I was starting to fall asleep, so I posted the photo and then woke up to my phone blowing up with messages."
Hoppus actually intended to send the photo to a small group of friends and family. However, he soon realised his mistake and then quickly drafted an official statement on his phone.
Mark previously revealed that he actually found his diagnosis to be "freeing".
The music star - who was diagnosed with a type of non-Hodgkin lymphoma - told the Guardian newspaper: "I really thought I was going to die. And, in a way, it absolutely was so freeing."
"I'd spent my whole life hypervigilant, thinking: what's the worst thing that could happen? And, oh, it's here now, I'm dealing with it and it still sucks."
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