First of all a luxury car is not an investment. A person doesn't buy a Ferrari, thinking it'll appreciate, they buy it to show off their wealth, and at a certain point, the 200K for a Ferrari is only a small portion of someone's income. And since high end cars tend to hold their value really well, they don't depreciate as much as regular ones.
Second of all, the lost opportunity cost is just the cost of owning a car. Live a little, you don't get to take the money with you when you die.
Finally, there are only a few types of millionaires who don't own a nice car. 1. those who lease the luxury car with their companies. 2. those who are always traveling for business, and who pay the $30K/yr to belong to those super car rental clubs. 3. those who see a car as just something to take you from point a to b.