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I guess what I'm trying to say is if it's a +EV bet but allowed only to take once then what's the point of EV? One bet means nothing EVwise unless proven over a large sample.
That's nonsense and I don't think you believe it.
Let's see:
You can roll a dye once for $1 but if you win you get $1 million. You would take that bet, wouldn't you? And you would take it because of its massive, positive Expected Value. You can refuse to use the term "EV" for non-recurring bets and replace it with any other term if you wish (what would it be?), but it is what it is.