I just thought of an analogy that may be very fitting. Few know this, but the first submarines used in combat were built during the US Civil War (or WoNA, whatever floats your boat). It was possible, but incredibly dangerous, and more than one was lost entirely.
Fast forward to WWI and WWII, where submarines were solid, dependable, and safe (to a large degree - not including combat of course). And on to the modern nuclear subs - downright luxurious in comparison.
So, Space Flight was in the Civil War era with the Apollo missions to the moon - we could do it, just, and it was incredibly dangerous, and we nearly lost one (13). The Shuttles were more of WWI tech level - still really dangerous, but doable on a regular basis.
We need to reach the stage in Space Flight analogous to nuclear subs, I think, before we can reach Mars. We just aren't there yet. And without wars to push the development (like it did subs) it may take a while.
That's why Mars is 20 years away. Still.