My feelings are mixed, but also generally don't get too excited about high prices, I am more excited about buying cars than selling them, I got in on a big Healey about 15 years ago when there were still deals to be had from time to time, At today's prices I doubt if I will ever buy another one, partly because they are so much money, partly because they are many other cool cars to own and I am realizing that my time and means to own are both decidedly finite. They are also a little less fun and a little more like an investment you feel obligated to protect and use wisely when they cost a lot of money. For that reason I am gravitating towards 70s and even 80s cars, most of which are not British, that can still be had for used car prices, and can be a lot of fun, and even some of those are creeping up.
There are some upsides to higher prices, you do have a hope of getting the restoration costs back out of the cars, and when you sell them you have more money to buy the next one (which is more expensive too, so kind of a mixed blessing)