2. If you couldn't trade money for interesting machines, then you'd likely do something else with it. If you could keep less of the money you earn than you do now, you'd probably continue doing exactly what you are doing now. In fact, you might work harder at it because you'd need to afford to buy those things that you really want. There is a point at which taxation is counter-productive, but I guarantee it is far below the level at which people can individually afford their own luxury yachts and private jets, especially when the pleasures these afford might be gotten by joining exclusive clubs that jointly can afford them.
3. Lead poisoning cause social welfare costs that persist across generations. The net utility gained by ensuring tens of thousands can be healthy and productive members of society instead of societal burdens far exceeds those you mention.
4. Suppose some very rich person spends an extra 100k on a golden toilet to replace his old silver toilet. I guarantee you that utility gained by that replacement is greatly exceeded by buying a homeless family a home with it. So, yeah, definitely, lets put the two on equal footing.