sum columns excluding collums with the same header as the value in a different columns

Hey All,

I would like to sum the values of second column and futher on but without the cell in the collumn with the same collumn header as the first cell in that particular row. So in th picture below i want to sum row 2024 without the cell in column 2024 and sum row 2025 without column 2025 and so on.

Does anyone have ideas how to do this? Thanks in advance for your reactions!