I'm sorry you don't feel great about your purchase. I ordered my 70D in May 2016, and got it in June. Almost a week after I had it they announced the 75. I looked at it, wow, extra range, etc., but then thought, wait a minute, why get upset? I have an awesome car that passed the litmus test of my decision to buy it!
I remember being at a supercharger about two months ago, and a guy with the older style S being really upset because he missed the refreshed nose. He was visibly upset that he didn't have the new nose. Now, here I am a couple months later, seeing the new S coming out with the new hardware for AP2.
So, the way I see it, you can do one of two things: Be upset, drive yourself crazy, or accept the fact that you are part of a bigger thing. I look at owning a Tesla as almost being part of a movement towards sustainable transport. This is an ever evolving moment. I mean, how great would Telsa be if it stopped evolving? Evolution means some things become, well, shall we say outdated, fairly quickly.
You can keep your S, or "evolve" later. I would recommend keeping you car. All the reasons you decided to buy it drove you to buy it, and now you own it. ENJOY it! It's a great car! I was very pleased with latest update. I just hit 5,000 miles and absolutely love my car. I'm totally cool with driving this one for several years before trading it in for a newer S. I love this company so much and the product, that I've reserved a Model 3 to boot. That will have the new stuff I'm thinking, and I can keep my "antique" S that I'm driving now.
No matter what, you now have, in your garage, one of the best freaking cars on the road, 5-star safety, autopilot, ELECTRIC vehicle that is zero emissions. Enjoy it! Drive it like you stole it and have fun! Learn the ropes of owning this unique vehicle. I think this would be better than trying to keep up with the latest and greatest... that could get pretty expensive with an evolving product like this.