Well people are free to wait for a sale or until the content catches up with their expectations.
I still play at least once a week, and driving around on planets is a blast.
This, basically, it will get cheaper, and as time passes, more content will be added to horizons making the value even better.
I was mildly disappointed with Elite when it first shipped. It wasn't a bad game, I felt it had parity with the original elite, however, which was good enough. As the year passed up until just before Horizons was released, they added so much to the game that it became something completely new and different.
If you're looking at it from a traditional game purchase expectation, yeah, I'm not surprised you were disappointed. Horizons today isn't the full game. It'll be added to and expanded upon over the next year or two. This is how E:D development has played out so far and they were very open about it, so it shouldn't have surprised anyone. If you need more than just "driving around a bit" then you probably should wait. It's also still very possible to get the base game on it's own for a very reasonable price, which includes the year of additional dev features that didn't ship with the game , and I have no doubt around the time the next expansion comes out, Horizons will have dipped down quite a ways as well and have a lot more added to it.
Patience is a virtue in this case. Personally, I'm having a blast and don't mind supporting the game. I had my reservations at the beginning, but Braben and his team have redeemed themselves, and proven, in my eyes, they're worthy of my trust on this game.