You may have missed it (A lot of spoilers! Only read if you finished it)

Sorry for the extremely long post, this movie resonated with me a lot.
This is the true essence of the movie that most people missed! (A LOT OF SPOILERS COMING UP)

Everyone believes that it is a "happy ending" with everyone acting "normally" in society at the end, when in reality Zach's character was the only one "normal". He was the one living, whereas the others are just living in society as a sort of cog in a machine (hence all the machine/future tech references). This is why in a way, you probably were not satisfied with the ending. I was hoping that he would realize that by taking the pills, he was removing his individuality (something he knew was going to happen, as he explained to the therapist). Owen Wilson's character realized this and that's why he decided he no longer wanted to be just a cog in the machine of normal society.

More out of life is possible! You just have to do what you love, and what you are passionate about. One of the scenes that resounded with me most was after Zach's character gave in and took the pills. He was talking to Amy Poehler's character saying something along the lines of, "I took the medication and became acutely aware of my limitations". But limitations are purely set by yourself! Yes, perhaps his idea to change society was grandiose, but what revolutionary ideas are not? All of what we see in society now was from the head of another person who was unafraid to challenge the social norms and believed that they could change the world. The medication made him feel like it was too big of a plan, but prior to taking it, he was so motivated, focused, and all because he found a true purpose in life and a means to carry it out (with his dad's money).

There is a lot more to this movie (in my opinion) than what is discussed. I had a friend of mine go under nearly the same storyline as Zach's character: Smoking weed/no motivation, an idea, motivated but paranoid, severe paranoia (to the point of near schizophrenia), medication, then mellowing out and returning back to societal norms. I followed the same arc as Owen Wilson's character where he was allowing the friend to follow his passions, stopped him when it looked like he was starting to be too much (like when Zach went to the amish house), and then almost wanted him to be "normal" again, then regretting it because I started to realize he was right, and that his drive disappeared when he began taking medication.

It also speaks on how humans have become so self-centered, only thinking about what is best for them without realizing the consequences of what is happening. Evidence to support that is the scene where Owen Wilson finally sees the neighbor naked after cutting down the oak tree only to realize that it wasn't worth it to end the life of the last oak tree in the area for pure personal gain. Another is when Owen Wilson kills the chicken and realizes how much it really means to eat another animal, but "normal" people (like his network boss) don't understand it saying "it's chicken", but not realizing the life that was taken to prepare the sandwich. Life becomes easy to ignore when it comes packaged and ready to serve, but when you have to work to take down a life you become more grateful for the rewards you reaped off the sacrifice of another.

There is another storyline as well that depicts Zach's character as crazy and hallucinatory, and has a "happy ending', but I think that that story line is the more "general" one that most viewers will see, but it is a very open-ended film, one that I related to very closely through my perspective.