N'raac, your constant revision of what's actually being said is not helping the conversation. You're the only one claiming that it was "trivially easy" to summon the Glabrezu. In fact, you're the only one claiming that it's easy to use Astral Projection either. No one said it was "trivial" just that it was plausibly possible.
It has been presented as a trivially simple matter in asserting the power discrepancy between warriors and wizards. Why, it should be willing to do virtually ANYTHING just to not have to sit in that magic circle for a few more days. It is now presented as a difficult task requiring extensive preparation, with a significant risk of failure at an extreme cost, when we discuss how unfair it is that the GM might apply the rules in a manner that results in the attempt being unsuccessful. Those difficulties and costs are not, of course, spelled out or quantified. With that in mind, if I am "revising what's actually being said", I think I have plenty of company.
I would see the player having much more grounds for complaint if they have put several game sessions of effort into setting the perfect summoning trap, and the ideal bargaining chips, to obtain that one singular Wish than I would when the player chirps out "I prepare my spells, spend the morning Taking 20 for the perfect diagram, cast my Dimensional Anchor, Magic Circle and Planar Binding, Summon a Glabrezu and tell him either I get my wish or he sits there - how can he possibly refuse? By the way, I'll be doing this every morning until something else comes up."
Like I said, I presumed that the PC would be evil if he's summoning demons to get wishes. An assumption on my part, I admit, but, I don't think it's a terribly far fetched one. So, again presuming a bit here, the wishes aren't likely going to be for fluffy kittens.
I can very easily see wishes an evil PC would make which would not meet the criteria of
used to create pain and suffering in the world
. A wish directed at the wizard's personal power, for example, would not "create pain and suffering in the world", though it may make life more difficult for the PC's rivals. A wish to deal with one or more rivals also seems quite plausible - and those rivals may well be just as evil as the wizard in question.
the glabrezu demands either terrible evil acts or great sacrifice as compensation
, which seems to indicate that a relatively mild evil action is not sufficient to satisfy him of the merits of granting the wish.
You also have not responded to the concern that, if this is a very "game time" consuming endeavour, we are ignoring all of the other PC's while the wizard plays his demon summoning solo quest. It was a GM crime of epic proportions when the rogue could participate, but his sneak attack wasn't useful. Why is it OK to play out several hours of wizardly preparations that the rest of the party isn't involved with at all so your Evil Wizard can cast a summoning spell?
But, then again, you're defending the DM in my example here. Which basically hits it right home. Here's a DM who watched, for sessions, as the players planned and worked on a goal, and then, just as they were about to do it, pulled the rug out and expected things to just be fine and dandy.
So what did the DM do while you spent session after session planning the perfect crime? Just sit there and say nothing? If so, I concur he was doing a poor job as a GM. If he has a concern with the direction the game is taking (and if, as you say, this planning went on for multiple game sessions, he should be able to see where the wind is blowing), then it should be raised and discussed. That does not mean he has to move his game to "cat burglar exploits", but he should be up front that this is not the game he wanted to run. I find it tough to envision the GM who sits quietly through several sessions of such planning, doing nothing and saying nothing, just to pull the rug out at the last minute. I could see a GM becoming more and more frustrated at the players' obvious disinterest in the game he thought he had volunteered to run finally saying "screw it - the jeweler packs up and leaves town - can we get back to the game now?", but dragging it out for several sessions of planning seems ridiculous to me.
Apparently, failure is simply not part of the equation?
Hussar did say "if they succeed" implying the players could fail.
There seems to be an explicit recognition of "failure as a possibility" when explicitly asked, but whatever the reason, any failure always seems to be a GM unfairly overriding the careful plans of the PC's, which otherwise would guarantee success. After all, they planned the heist long and hard, so it should succeed. And they planned the demon summoning with great care and effort, so they should get their wish. That the GM should raise a possibility of failure just because of the rules is completely unreasonable.
I can only see what is posted, so I'm somewhat confused regarding Hussar's real reaction to failure in game. Every time I have seen him post an experience where he did not get what he wanted, it seems to end with him denigrating the GM and either walking out or wishing he had, but he does seem prone to hyperbole, and the nature of the discussion is such that he's logically going to post very negative experiences, so the extent to which it is reasonable to extrapolate these anecdotes to his routine gaming experiences and behaviour is less than clear.
True, but I think it's very telling that he left that unsaid.
Who says the DM can't let the players pursue a course of action and then later render it untenable? I'm imagining the Fellowship scaling Caradhras, getting trapped in snow, and some player stopping the game and complaining to the DM about how he misled them by letting them try to scale the mountain. Stuff happens.
His position seems to be that the players can fail by their own bad decisions or bad dice rolls, but that the DM cannot allow them to fail otherwise. Which doesn't sound that bad until you start considering the implications.
I will admit to some curiosity as to his reaction if they had gotten half way through their heist to discover that there were magical protections they had been unaware of which now frustrated their plans. Of course, I can't tell whether they should have been aware of these from their weeks of preparation, or whether they would eventually come to a point in the plan where it was simply not possible for them to have perfect information.