My personal feeling as an early-30s who has seen numerous "impossible" projects come and go is that it does help to know what has come before you and to have an idea of why you're going to avoid the way your previous people failed. From what I can see, when people who didn't know "it" is impossible succeed, it isn't because of tenacity or persistence
per se, it's because they, in their ignorance of the accepted "right way" to do it, end up trying something new that ends up working.
And of course it should be pointed out that the way it becomes accepted wisdom that "it" is impossible is usually young idealistic people who don't know it is impossible trying it and failing repeatedly. The narrative that you can overcome that sort of problem by sheer persistence is very tempting but also very dangerous; you can lose years, decades, or even entire careers trying to follow it.
As a concrete example, one that comes up a lot and I try to offer a, err, "calming" voice on is the persistent idea that there should be some sort of purely-visual programming language. The advice I offer is not "don't do it"; the advice I offer is go out and look at the immense amounts of work already done, learn why they failed, then explain why you will not suffer from the exact same problems and fail in the exact same way. If you come up with such an explanation, go for it! No sarcasm, no joke, go for it with my blessing. But this particular area has been richly covered and extensively explored already, and especially if you think you want to make money with this idea it behooves you to take advantage of the nearly-free research you can do simply by looking at others.
After all, you might succeed. Tablets were an "impossible" project pretty recently, until Apple succeeded. Times do change, processor power has continued to get cheaper and cheaper (one of the reasons tablets have succeeded now, IMHO, you can still have a decent experience on them), server infrastructure is cheaper than ever, programming languages have continued their slow-but-steady march towards having more power than ever, etc.