Phil talking right now about how if when he lost his helicopter job he wasn't able to turn his hobby of streaming into a 'career', his life would have been 'ruined forever, I would have been completely screwed'.
It seems to me that it was his decision to do that that was what 'completely screwed' him. He went into it with no backup plan or intention of using it to learn new skills that he could build on (something like video editing) like a lot of actually successful content creators have done. He struck gold, and the only thing he did with it was to live extravagantly with the attitude that it was going to last forever. He got a few debt free years where he could live like a big shot and then made the ridiculous choice to move into a big shot house with his girlfriend, immediately putting himself into new debt and cutting ties with anybody who was an actual friend who could maybe call him out of hold him accountable for his bad decisions.
If he instead had used the prosperous time he was so fortunate to have after losing a job when things were hard all over and during which he was able to pay all his bills and still have plenty leftover to save for the future, he could also have been pursuing, in his off time, something that utilized his education and degree long-term that would have given him some stability.
There's nothing wrong with lucking into something like making thousands a month for streaming games especially if it's something you really enjoyed, like I assume it was for him at the beginning. That's a dream come true for a lot of people. His mistake was treating it as if it would go on forever with no additional effort needed on his part. He refused to learn even the basics of what his new 'career' entailed when it came to technical skills, he refused to listen to anyone who suggested he do things differently instead of having someone that he could have honest conversations with about the best way to do things (because then he'd have to share some of the profits of his success with them probably), and he never thought about what he'd if things didn't remain exactly as they were ('there never WAS a 'plan B'')
Getting into streaming wasn't the biggest mistake he ever made, but everything about the way he did it was. The sad thing is that he's so deluded himself that all the major things that have gone wrong in his life are the fault of other people, he'd probably say, 'If I had to do it all over again, I'd make the same decision'.