Go to Brazil, heart-of-palm is in basically every salad bar anywhere, as common as lettuce and tomatoes. Just a normal and normal-priced vegetable, very mild flavor.
A lot of vegetables kill the plant that produces them... and the heart-of-palm that is canned and sold is produced from farmed palms that aren't coconut palms.
Millionaire's cabbage seems to refer to Millionaire's salad which seems to be specific to the use of Deckenia nobilis, which are a protected species due to illegal over-harvesting. So the assertion that the term "millionaires cabbage" is funny because heart of palm is common in brazil seems disingenuous.
"Hearts of palm are the growing stem tips of various palm trees, especially the South American peach palm Bactris gasipaes, which readily resprouts after its tip is cut....[Harvesting] hearts of other palms often results in the wasteful death of the entire tree."
(emphasis mine)
[0]https://books.google.com/books?id=bKVCtH4AjwgC&lpg=PA316&vq=...