Your response assumes that racism is in the past. Racism still exists. White supremacy still exists. White people are still privileged--ie unjustly receive enrichment, often at POCs and most often at Black peoples' expense.
That is why people who arrived 'after abolition' are still responsible: because ALL Americans benefit from the work of African American slaves and the poaching of Native/Indigenous land. White people still benefit: it is highly irresponsible to disregard this, because to do so is akin to maintaining our white supremacist system.
Current problems cannot be solved by relegating them to the past, because this shirks responsibility. Current problems--embedded as they are in our very active white supremacist system which at this moment benefits white people--must be addressed as if they are current problems. That means admitting white privilege.
As for your comment re: suicide and mental health problems, these causes are multifactorial based on multiple studies. Two theories are the reality that economics imposes along with the internalized sense of superiority which now clashes with reality for these men: their privilege is eroding while others are rising up from untermensch status. This is hardly a tragedy, and should be embraced as forward movement. Any white man who benefits from a white supremacist system AND embraces this should feel obligated to understand why it damages so many other people. Now, not just before 1865.
I would love an explanation for why certain Irish people adhere so desperately to their 'victimization.' I've heard about 'Irish slaves,' one popular white supremacist trope, and often about how 'we came here AFTER slavery ended.' Why is it that this one group adheres more desperately to alleged victimization than virtually any other privileged group?