The satisfaction derived is the same between the un-drawn lottery ticket and how good it is going to be for my heirs when they get my stuff. Both can only be enjoyed prior to the actual "drawing" in that they are both fantasies that can only be enjoyed before the fact.
Actually, one could say that it is at least possible that one will see the realization of the lottery fantasy.
Actions taken to try to achieve a result after death can only be enjoyed or appreciated as fantasy, even if they actually do turn out exactly as hoped, since the one doing the hoping will no longer exist after the action takes effect.
I think you're thinking more chronologically while I'm thinking more probabilistically:
But the reality of the inheritance coming to fruition is quite large (as far as I know, barring unusual circumstances, it is in fact
guaranteed). For the lottery ticket: Vanishingly small. The satisfaction of a pipe dream lottery win is absolutely not the same as the satisfaction of a well planned and solidly probable benefit for someone. You're introducing a chronological element where there doesn't need to be one: It makes one feel better
now that they've planned for their children's future without them. Of course it doesn't affect the deceased one
after they've deceased: It affects the survivors in the future and that is comforting to those still alive in the present. And this isn't some futile probability game like the lottery: It's actually part of law.
Do you feel the same way about organ donation? You know it
does make a difference to those receiving the inheritance or the donation, even if you aren't around to witness the difference you make. For some people that means a lot
while they are alive. If it means nothing to you then, well, I can't help you.
Anyway, there's no requirement that satisfaction can only be obtained at when a decision comes to fruition. Knowing that your loved ones will be provided for in the future after you've passed is satisfying to many people while they are still alive.