Costco really incentivizes shopping in bulk, from the huge value-pack sized portions to the focus on frozen & dry goods to the super-sized carts to the anxiety-inducing shopping experience. My wife and I shoot to go no more than once a quarter, just because it's a hassle.
We found our habits (and need for Costco) changed dramatically once we moved into a home and could now put in a chest freezer and pile toilet paper rolls in a corner.
I actually only got Costco originally when I lived in Hawaii and it's kinda a requirement there but kept it cause it's actually really nice.
Maybe savings are that large if you're comparing against regular prices at retailers, but if you wait for sales, they're as cheap, if not cheaper than Costco.
I heard you can also get someone with a membership to buy you a gift card, and use the reloadable gift card for continued access. (Or buy one for yourself and then cancel your membership.)
I think one danger with Costco is that it encourages overconsumption. It may feel like you're saving money - but you'd save even more just not buying a robot vaccum or VR headset.
If you do the research and decide you would benefit from a robot vacuum, compare different models to decide on the best fit for your needs, and then check prices at different stores and find that it's cheapest at Costco - then yeah I'd say you're saving money. But I'd venture to guess that most robot vacuums are just bought on impulse during Black Friday sales (for example) - which I don't think counts as saving money even if you get a big discount from the MSRP.
To be fair, this isn't a problem unique to Costco. I'm guilty of buying a lot of junk on Amazon.
That sounds like you might well be spending more time than the money you're saving.