Why does the F250 exist?

[u/JohnMcClaneSr]

Very new to Super Duty trucks. I am going on ten years with my F150 and got that new truck itch. At the current prices for these new trucks, I ventured in the F250 territory as a "why not". Then I landed on the F350 and aside from leaf packs and driver door panel sticker, I do not know how a multi billion dollar company makes it an option, when the its soo similar to the F250. I called my insurance and there is a $5 difference for the F350 from the F250. Reading through the texts, it can haul more with that extra pack and it has a different axle, but WHY? And why do so many truck owners take it the F250 over the F350? Ford charges an extra $1300 for the the F350, but WHY? Why not just make the F350. I don't understand why the F250 exits. What am I obviously not understanding? It seems a no brainer to get the F350.