Asking a bunch of junkies and investors will always result in a ‘do it’ consensus
I would look at what percent of your cash on hand this represents, and the ease of selling it. Being able to pay for it in cash doesn’t mean tossing most of your savings account at a baseball card is wise, though it’s better than 401K draining. A rare card often has few buyers looking for it. If your gut says it is fiscally irresponsible, even though you want it and your bias is of course to do it, that’s the clue not to do it.