-'Glad you've found your own family"
-I fear that statement could upset a lot of adopters and adoptees
-maybe that statement will upset adoptees and adopters but it is still a valid point.
Adoptive parents are a child's real parents. To suggest otherwise is abhorrent. Lots of parents are shit parents, unfortunately that will also be true of some adoptive parents. With the checks that adopters go though these days that's a lot less likely than for other methods of becoming a parent.
the adopters usually have to grieve for the children that they can't give birth to naturally
Many, many adoptive parents are perfectly able to conceive naturally. Anyone who has fertility issues has to go through a process of reconciliation with that. It doesn't mean that adoptees are not 'their own family'.
Adopted people have higher rates of depression, suicide, crime, mental health issues and so on.
Correlation is not the same as causation. There are reasons why modern adoptees experience much greater levels of difficulty than the general populace. Those reasons are why they were adopted, or weaknesses in the care system, not because they were adopted. The outcomes for children who've been abused, neglected or had a poor in utero environment (sadly a majority of modern UK adoptions) are a lot worse if they are left with the people doing the harm.