You talked about people doing anything they wanted..
That is inclusive of their car crashing at a high rate of speed with only them losing their lives, so yes costing insurance companies..
Are those okay with the stability of the family--medical, emotional, etc .
going 40 is twice as much as 20 in velocity, but FOUR times the KINETIC ENERGY..
Slow down in town .
I fully agree with slow down in down in town and overall around others. I don't think the chance someone somewhere might come into the picture in another vehicle suddenly creates horrific dangers for someone driving very fast on an open highway - and certainly not in relation to other life dangers people cause to others.
As for stability, insurance etc, many hobbies, sports and recreational activities, are very dangerous. And I have no doubt there will be increasing pushes to outlaw and with increasing major penalties all those too.
It also takes exponentially increasing amounts of power to accelerate and move a car once a car hits about 100, and only true super cars with the areodynamics to match can get past 160. The fabulous Lambrogheni Contact could only do 150 mph top speed, 160 if they removed the rear wing (which was dangerous to do at high speeds). By the 1980s, the fastest production cars made - even super exotics - couldn't reach 170 mph. Given 1950s Jaguars could reach 140, this wasn't much of a gain.
It has only been the last few years that production cars, even the most exotic, could really go over 200 mph, despite claims otherwise. Most making such a claim still can't and peak out in the 190s.
Tire technology isn't much good over 200 mph for continuous driving either. The fastest of all production cars, Buggati at 256 mph has tires that cost $10,000 each. When tested for the Buggati's weight, the tires are good for only 1 such run with safety and 2 only a possibility. When tested for 3 such 250 mph runs, nearly always 1 of the 4 will blow.
The current limiting factor on super cars is NOT horsepower. It no longer even is areodynamics. It is tire technology.