You don't need to be a millionaire to make friends.
Edit: If you want to. Being a millionaire gives you the chance to choose to spend time with friends instead of doing chores, because you can pay people to do chores.
(Trust-fund kids, on the other hand, do have a lot of time for socializing. Unclear whether they are happier than others or not, though.)
Do you really mean that? Do you find that those who achieve are the most likely to have "a lot more time" to focus on their interpersonal relationships?
Beyond a modest income, my experiences do not line up. This is almost the same reason that I believe the 20th century conception of retirement is a bit silly.
Even the ones that are still working have plenty of time to spend with friends, because they hire people to do chores like cleaning and folding laundry, and then pay for takeout food to save time on cooking and dishes.
It isn't a necessary conclusion.
That was my point -- that having millions gives you a lot of freedom to choose how you spend your time.
I find that learning stuff and being able to do things improve my relationships dramatically. You got to have something to be able to give back.