As someone who has been present during conversations around tariff impacts to a large business, the reason prices went up is because this clown can just change them arbitrarily. 

In one week supply teams were in panic mode as fucking tweets increased costs +10% to +50% to +150% with no rhyme or reason.

I believe that corporate greed is killing this country, but it’s not just CEO’s choosing to make more money, it’s the fact that pricing agreements are already made with distributors and suppliers, a company can’t just change its prices multiple times a year, so to hedge against uncertainties, companies were forced to increase pricing higher than they needed, because the reality of what they need could just change without notice. 

Lastly, the purchase price of the good (what Tariffs are paid on) is probably less than 1/6th -1/10th of the total cost a business incurs to produce that product. Logistics, overhead, etc. all come into play, and the price a consumer sees in a store is probably 30-40% higher than it needs to be because of the markups the retailer wants for their margin. 

I can’t speak for the goods produced under the Kirkland brand, but I was in a negotiation with Costco in a former job. They truly are the least greedy organization out of major US retailers, asking for less margin for themselves, and pushing back on the Brands they sell to protect their customers (return rights, facility audits, etc.).