In my case, with my IM6, my big outlay was right at the beginning, and it's only been oil changes/checkups since then, plus trying to solve the CV issue, which has consumed more time than money.
I sold my last two Intermeccanicas for what I paid for them, so it's been a relatively cheap hobby up to when I dove into my current build.
I don't anticipate getting my money back when I do sell my IM6, but it's a hobby, and you can't think of it any other way. I do have a file where I keep my receipts, and so far it hasn't been painful at all.
What else can you do with money, other than spend it or give it away? And if you have all of life's necessities covered, feel confident that you'll have enough until the end with enough to give to the kids and grandkids when they need it, then do so.