A philosophical question...
I disagree, and I feel that I've got to say so somewhere (since I don't usually have the chance to directly counter the people who purport the opposite). I enjoy poker as a game in which the object is to amass the largest portion of the available chips as possible, but real gain beyond the internal context of the game is NOT necessary in order for me to enjoy it. I liken it to many other games, especially many board games, in which other tokens are being amassed, whether they be fake money in Monopoly and its cousins, or other racing games where distance along a trail is being amassed (a measurable progress for comparison, just like money or chips, and thus still the same game philosophy). I would equally like to get together with a group of friends to play a friendly game for no external stakes as heading to the casino...
...unfortunately, there is another side to this. While I take the game seriously enough to keep it strategically equitable and challenging, I have noticed that many other people do not if there are not stakes attached. The result is that many friendly games, and especially those available with strangers and the general public, are almost unplayable for the non-strategical risktaking of the other players. When there is another game waiting as soon as you lose and nothing to be won but the fun of the playing and the bragging rights of the win, the result is usually a large body of players who will go "all-in" with almost any two cards, fully prepared to shrug off the deserved loss when called and just start a new game, but also aware that people trying to play the game in its honest, strategic, intended manner are usually going to be unable or unwilling to call the all-in, even though they know it to be nothing but a blind and foolish bluff.
Since my friends are usually far too busy for a friendly game outside of the planned monthly tournaments, the only options for friendly play and practice are with strangers, and the only source of stranger competitors are casinos and online... and the only no-stakes games are rife with the nonsense described above. It's pretty frustrating.
Am I very unique and alone in my enjoyment of the game for the game's sake? Is it really the case that almost all other poker players out there are only playing for the external reward of personal gain beyond the context of the internal game? It is inarguably a depressing prospect...