Would you be surprised that we have dozens of nuclear plants all over the United States? Modern reactors that can withstand the mistakes of the past without the disaster? Media makes the public think the risk is higher than it is when in reality, more people have died per year installing renewables than all the nuclear disasters combined (per GW/H).
Nuclear is simply too energy dense to ignore.
Hard to determine with what we know. We haven't met any other intelligent species which suggests we've passed the filter. Yet, making that conclusion before knowing there are no others to meet is too presumptuous. But, if I were to guess, I'd think the filter is adaptability.
We're superior to animals for being able to use tools, live in radically different climates, and shape every spot on earth into a livable climate. Even on Mars, the moon, and space. How else would a species venture through space if they can't adapt?
That might be too general a concept for the question though.