I don't know if other forms of rental income, say invest in some kind of housing, would be considered unearned income. Maybe I should look it up.
I am not what I would call wealthy and it makes a huge difference of what kinds of income I'm taxed on. Some of that is unearned income which I pay income tax on but not SS or Medicare.
And I had some fun trading stocks a couple years back and all of what I made was taxed as short-term cap gains ordinary income. It had a negative impact on the rest of my tax situation, so it had a dampening effect unless I make huge amounts which I wasn't good enough at it to do. IOW it wasn't worth the hassle for no more than what I made.
I guess the only CERTAINTY I can fathom and know is that regardless of however you make your money, the government will find a way to take as much of it as they can from you.
Hopefully, you would also have the resources of a good lawyer and knowledgeable account to advise you but in the end, even in death, this government finds a way to f@ck you.