biggestdan wrote:What am I missing?
You probably won't find a single card that maximizes each of your spend categories. And there's no single "best card for big spenders". Best is always highly subjective. Big is as well. Based on your OP you don't seem to mean "big" as in Centurion big. Avoid using such words and stick to numbers and specifics that we can use for recommendations.
At $500/month on groceries you might want to reconsider your "no cap" requirement as that would easily fit in to the BCP's $6K limit. You can do the math to compare 6% on groceries with the BCP versus other cards with lower rewards but no limit to determine the break even point.
Also consider how rewards are redeemed. The TrueEarnings issues you the reward once a year and if you want cash you'd need to redeem at Costco. With the BCP you can request statement credits as desired based on what you have accumulated in your rewards account. However, BCP cash back rewards are restricted to certain increments.
As yet another example, my PenFed Platinum Cash Rewards card automatically issues statement credits each month.
Compare and select what suits you best. You have to decide where you're willing to compromise.