You ruined the experiment! Not a question, but I do feel genuinely bad for any distress that I've caused.
Neither Sam nor anyone else that participated "ruined" the experiment. They added to the data on what happens when you run the experiment. The key point here is that Jonathan ran, in his own words, an experiment. Not a service with a mission or a protected outcome, but an experiment. If anything, it exposes weaknesses in the plan that future implementors can correct.
Some of the misunderstanding might be which kind of experiment it was. In the scientific usage of experiment, you're right. But there's also an informal usage of the word, where, for example, you might call the Hacker Dojo an "experiment in building community spaces". There's a strong implication there that you're not supposed to actively try to screw up the Hacker Dojo, because it's not really an experiment in that sense, but only in the sense that a lot of tinkering with ("experimenting with") different ways of doing things is encouraged---if you're doing it in good faith and in line with the endeavor's shared goals.
In this case I can see how people could interpret it either way. Unlike in the Hacker Dojo case, it doesn't seem as inherently clear to me that there was a strong expectation of good faith; buying coffee is a sort of unimportant enough thing that many people might've assumed Jonathan's motivation really was more of a "let's see what happens" type experiment, rather than a genuine attempt to make social-coffee-buying work.
totally agree. Sam's action is a variable/result of the experiment. i don't think the experiment looked for a linear binary result/pattern on cash in/out. this experiment has caused a human being to question and think about another human action, and Sam's action has resulted in a great, publicly shared, outcome. to him i say "chapeau"!
Neither Sam nor anyone else that participated "ruined" the experiment. They added to the data on what happens when you run the experiment. The key point here is that Jonathan ran, in his own words, an experiment. Not a service with a mission or a protected outcome, but an experiment. If anything, it exposes weaknesses in the plan that future implementors can correct.