The assumption that Russia is a superpower and that russian victory is inevitable is the reason Russia has been making a fool of itself in Ukraine these last 6 months. There is no reason for outsiders to make the same mistake.
You know Russia doesnt stand a chance in a conventional war against the USA, so why pretend they do. But youre right about asking the US to come to Ukraine or Russia, because unlike Russia the US has real projection power.
And there is no point mentioning nuclear weapons since the US has the same capacity, unless your argument is the russians are more insane than the americans.