It's a lot but for my main points: The ends may not justify the means, for example, killing an innocent person to save many people's lives is not a morally justifiable action. In my opinion, it's also unrealistic to measure happiness. It assumes that we can measure and compare the happiness of different people, but in reality, this may not be accurate. The other thing too is that it puts too much emphasis on maximizing the overall happiness of the majority. This could result in the minority or marginalized groups being neglected or, in some cases, exploited. I just feel like it's something I don't see myself ever believing.