I see numerous hot and furious debates about Collector VS Investor all the time everywhere. My simple take on it is: If your hobby can bring you joy and cash when you need it, why not?
Who set the rules we should not make money from our hobbies? Who set the rules Pokemon cards should only be played by children? Nobody cares!
*My 2 cents opinion as a collector, though haven’t sold any big ticket cards > $1,000 yet. Merely let go cheap cards <$200 to streamline collection.