It appears to be a case of obsession and possession.
On one hand, a lot of members are pretty quick to claim that Prophet Muhammad came to this world for the sake of all the people all over the world, on the other hand, the same members cannot tolerate that Ahmadiyyas take the Islamic Prophet as their own too.
At the same time, Islam also considers Jesus as its prophet (or messenger, howsoever you take it), who also happens to be the last prophet of the Christians.
It seems to me that whatever happened in Islam, with regard to taking some other religion's last prophet and turning him into a junior/'second last' to their own, is exactly the same thing that happened in Ahmadiyya, turning Islam's last Prophet into the 'second last' one, and then bringing out their own prophet (Mirza Ghulam Ahmad) as the final one.
But I do not see Muslims getting persecuted by Christians for that specific reason anywhere in the world.
Ahmadiyyas are already considered non-Muslim by those who believe in the finality of Prophet Muhammad. It should stop at that.
Why persecute them simply because they too feel a right to include Prophet Muhammad in their own religion? He (Prophet Muhammad) is, after all, for everyone, right?
P.S. If there appears any misunderstanding leading to any misinformation in my post, please feel free to point out, with arguments, and with facts.