Re: Other peoples money...
You are aware that the "slippery slope" is a logical fallacy, not a well formed argument?
In this case, there is no empirical evidence (that anyone has pointed out, anyway) that tax thresholds tend to work downward in the way you describe. Granted, they will move downward by fiscal drag, but that's a much (much) slower process than you're talking about, reckoning at least half a century to get from $10 million to $1 million.
I'm also not aware of any evidence that higher marginal tax rates correlate with higher inflation. Perhaps you would like to link to some?