Earlier quoted context omitted.
You can put a wealth tax on billionaires without putting taxes on poverty level workers ($500/month in the US). You're making bizarre nonsensical arguments here--slippery slope, strawman, etc.
That was clearly not the point. The point is there's always someone with a different bar for what is excessive wealth. Chances are that 80%+ of the world population would find your income staggering, the same way you consider a billionaire's wealth staggering. So how do you decide who's scale to use?
Like the way all other murky subjects are settled, you just decide on one. We don't legalize murder just because some slayings are justified. The existence of grays areas does not preclude the black and white.