Inflation Beneficiaries - Costco Winning the Grocery Wars?

I recently moved, and it made sense to get a Costco membership for the first time in my life (I had benefited from somebody else's membership until this point).

In an average week, I use roughly 2.5-3 16oz packs of greens. At HEB, the cost was $4.98. A comparable product at Costco was $3.88 - a savings of 22%! Over the course of a year, I would save $143 on this one item at the current prices - an over 139% return on my investment of a $60 membership card.

This does not take into account the fact that all other product savings are now "free" - the return on the Costco card with savings like these can be ridiculous, and definitely well worth the cost!

The catch is that product quality varies drastically at Costco - some items are solid buys, like the greens, but others are highly questionable when it comes to taste due to additions of chemicals like boric acid (in seafood). Alternatives (Sprouts and Whole Foods) can have significantly better quality. The question is - what is the priority for you?

The implications for inflation should be obvious - Costco should be the best buy for anyone who eats organic greens or other similar items, provided they maintain the same price differential. The higher inflation goes, the more Costco benefits as member budgets are squeezed. Given a higher cost of gas and reduced time during high inflation for other activities, Costco is creating a moat for their business, relative to the competition! The only question is whether the organic greens are a "loss leader" for them.

What are your thoughts, and what types of breakdowns are useful?