Loads of people on this forum have told me it'll be ok, they don't know any better than anyone else.
You're an intelligent person, but you've got a remarkable ability to take things out of context!
Back when I was dx'd I was getting angry because I knew very little about it, and nor did the people who were telling me I'd be fine.
But move on 30 years, and having learned more about it, my own experience is that, hmm, let me have a look at my results, yep, I'm doing fine.
Sure, that's a sample size of 1 and anecdotal. But there's been dozens of people on this site telling you similar stories.
And formal studies like DCCT, which say that provided you pay a bit of attention to levels, there's a pretty good chance of avoiding complications. No guarantees, of course, but we've got to run with what we've got.
The advice you've been given that it will be ok is always heavily caveated by the fact that T1 is unpredictable, there's no guarantees, but you can't possibly deny the fact that it is coming from people who do know what they are talking about, having lived it for decades, and have done well.
It's up to you what you do with it. You can spend the next x decades moping about statistical risks, or just say, aye, ok, no guarantees, but chances are it'll pan out ok.