If you throw yourself off a cliff because only defeatists accept that they can't fly by flapping their arms, you aren't brave taking chances, you're committing suicide.
By the same token "we don't want to be defeated" isn't a good reason to create a planetary exploration timeline driven by false urgency. Mars isn't going anywhere.
There's a difference between something being extremely difficult and it being actually impossible.
And yes, Mars is not going anywhere, but the same cannot so confidently be said about our ability to get there. Our species has been capable of spaceflight for a tiny fraction of our existence and there is plenty of precedent for catastrophic loss of knowledge and capability.