the idea isn't that I need to prove that pleasure isn't the sole source of value. What needs to be proven is the idea that pleasure = the sole source of value. This isn't immediately clear.
Consider the fact is that whenever we seek pleasure, we seek it in things that bring us pleasure. However, if we could choose to grant ourselves object-less, endless pleasure in and of itself, we wouldn't.
The idea is that pleasure is just indicative of other valuable things, like novelty, justice, harmony, virtue, etc. Some people think that these things aren't at all pleasurable. Sure, but its easy to say that they're still valuable for other reasons.>mercy killings>not usually controversial
most people who aren't hedonists oppose them, usually on the grounds that human life is invaluable. They think this for much the same reason as your claim that >'It's hard to argue that anyone could rationally evaluate their future and balance their own happiness and sadness to determine if the most logical choice is to kill themselves.'