On your argument about tradeoffs, people make choices all the time where they accept some very small risk of some very severe suffering in order to increase their happiness by a modest amount. For example: cycling along a busy road to visit their friend. If you say that no amount of happiness can make up for the trauma of being involved in a serious accident, then it seems like you are forced to say that this choice is wrong. That seems like a strange conclusion to me.
I agree with your title, but I don’t think negative utilitarianism is the answer. I like Toby Ord’s essay on this, “Why I’m Not a Negative Utilitarian”: https://www.amirrorclear.net/academic/ideas/negative-utilitarianism/
On your argument about tradeoffs, people make choices all the time where they accept some very small risk of some very severe suffering in order to increase their happiness by a modest amount. For example: cycling along a busy road to visit their friend. If you say that no amount of happiness can make up for the trauma of being involved in a serious accident, then it seems like you are forced to say that this choice is wrong. That seems like a strange conclusion to me.