Former NFL player Michael Oher claimed that he was never legally adopted

because they don't actually have that money in their bank/savings yet. if they decided to pull everything together to get cash right now, I'm not sure they'll have over $1M.
they are not fully retired. he retired at 58 (the plant he worked at does some kind of point system age + years of service) and was just drawing from pension or what ever until he reach 65. they both saved well outside of retirement. she got forced retired and they gave her 3 years salary to walk away from her job (not lump sum, drawing normal monthly salary). now when they fully retire they may be millionaires.. but they will have another (hopefully) 20+ years to live off of that.
Well, as I said, I know quite a number of "quiet millionaires" who have gotten to where your in-laws are going. And they are quite content with what they have.

That said, I think know what you intended -- but although being a "technical" millionaire isn't what it used to be, it's still a buttload of money, and many of the people I know in that situation do NOT take what they have for granted or have the more-money envy you refer to. I have noticed though that where they came from is a great indicator of their keep-up-with-the-Jones mentality or, rather, lack thereof.