You may mock Roosevelt, but perhaps he was aware, as you seemingly aren't, of how many past civilisations have collapsed due to timber crises... Easter Island being one of the most dramatic. What if someone hadn't invented creosote coatings? Sure, technology provided a solution that time, and many other times in recent history, but there are plenty of other times it hasn't.
Our modern global/western civilisation is big and impressive, I'll give it that. But if you take the historical perspective, the number of civilisations that have collapsed is quite a long list, and some of them were quite big and impressive, too.
So yeah, we've got lots of scientists. You think we're the first civilisation to have lots of scientists? Sure, we're more advanced than our predecessors, but do you really think that our civilisation's size, or even technology like the internet makes us so different from all other civilisations to come before us, that we're immune to collapse? On the contrary, our current civilisation is so big that most efforts to make significant changes seem almost completely ineffectual. And that oil is going to run out.
I've certainly not abandoned hope, but I'd like to think I've got beyond the mindset of thinking that people in history were so radically different from us. Technology may well provide a solution to all our problems, but it also might not. Isn't it wise to prepare, at least slightly, for that eventuality? Isn't believing otherwise just placing blind faith in a deus ex machina?