First of all, the OP mentioned nothing about kollel (as has been pointed out). I’m not sure what it’s doing in this conversation at all.
Secondly, I flatly do not believe the claim that “This is widespread”. I do not believe that it is “widespread” for children to demand down payments on their homes from the parents. Nor do I believe that it is common that “When you speak to the married children they whine, when you dont speak to them, they say you never call because you dont care”. I simply don’t believe this is the case.