Yes, there are people who feel the same way you do (hi!). Just like there are people here who love eating out, or love traveling, or whatever else. The key is to recognize that life is an "or," not an "and," and to deploy your money strategically and efficiently to bring you maximum value. There are worse things to blow your money on than something that brings you joy every single day.
So, can you afford a Miata? What's the rest of your life like? Do you have other splurges, other wants that you find excuses to spend money on, or is this really IT for you? Are you on track to FIRE when you want? How much longer will you need to work to cover the cost of a Miata in perpetuity? Not this same car, mind you, but some car like it, because once you splurge you are unlikely to want to go back -- and don't forget maintenance, insurance, etc. Is that extra time at work worth it? Can you write a check for the car, or do you need a loan? (Note that I am not saying you should write a check -- if you can get a super-low interest rate, a loan may be a reasonable choice. But needing a loan for a fun car means you can't afford a fun car.)
If the rest of your life is on track and you're willing to work the extra time to cover the cost of buying and maintaining an upgraded car, then yeah, a used Miata is a pretty cost-effective way to deploy your StupidCar money.