Diamond status is bundled with Aspire ($450), not the free card.
We don’t have aspire. My Amex bill that we pay off every month is about 7-8k a month. We started at I think gold and have spent our way up to diamond. We are lucky if the bill is only about 2k a month.
ETA: we have had this card for about a decade or more. Maybe we started as silver… I can’t remember.